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Suzuki T, Mitake S, Murata S. Presence of up-stream and downstream components of a mitogen-activated protein kinase pathway in the PSD of the rat forebrain. Brain Res 1999; 840:36-44. [PMID: 10517950 DOI: 10.1016/s0006-8993(99)01762-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We previously reported the presence of Erk2 type mitogen-activated protein kinase (MAPK) and enrichment of its substrates in the post-synaptic density (PSD) fraction, and suggested a role for MAPK in the synaptic transmission and its modulation [Suzuki, T., Okumura-Noji, K., Nishida, E., ERK2-type mitogen-activated protein kinase (MAPK) and its substrates in post-synaptic density fractions from the rat brain, Neurosci. Res., 22 (1995) 277-285.]. In this paper, synaptic localization of the upstream and downstream components of a MAPK cascade was examined. We found that RSK1, Sos1, N-Shc 66 kDa, N-Shc 52 kDa, and Grb2 were present in the PSD fraction, and cPLA(2) was present in the synaptic plasma membrane fraction. RSK2, Sos2, and N-Shc 46 kDa were not present in the PSD fraction. Post-synaptic localization of RSK1 and Sos1 was confirmed by immunohistochemical examination at the electron microscopic level: the two immunoreactivities were localized in the PSDs, both in the spines and dendrites. These results suggest that all the MAPK cascade components examined were associated with PSD or the synaptic plasma membrane, suggesting the role(s) of the MAPK cascade for synaptic transmission and its regulation at post-synaptic sites.
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Affiliation(s)
- T Suzuki
- Department of Neuroplasticity, Research Center on Aging and Adaptation, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Japan.
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2
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Cussac D, Leblanc P, L'Heritier A, Bertoglio J, Lang P, Kordon C, Enjalbert A, Saltarelli D. Rho proteins are localized with different membrane compartments involved in vesicular trafficking in anterior pituitary cells. Mol Cell Endocrinol 1996; 119:195-206. [PMID: 8807639 DOI: 10.1016/0303-7207(96)03814-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In order to explore the role of certain GTP binding proteins in the rat anterior pituitary, we have analyzed the subcellular distribution of the proteins rho and rab. They were found in both membrane and cytosolic fractions. Rab1 and rab2 were localized in both Golgi and endoplasmic reticulum (ER) membranes, while rab4 and rab6 were found in fractions enriched with Golgi and plasma membranes, implicating these proteins in the control of vesicular intracellular trafficking as described in other systems. Rab3 was localized like a fraction of synaptophysin, suggesting a role for rab3 in the targeting of "synaptic-like' microvesicles. We have identified three substrates of C. botulinum exoenzyme C3. A 26-kDa substrate with an isoelectric point (pI) of 5.2, probably rhoB, was localized in the lightest fractions such as rab3 and synaptophysin proteins. Two other 23-24 kDa substrates with pI of 5.5-5.8, probably rhoA and/or rhoC, were found in both fractions enriched with ER and secretory granules. Rho proteins have been implicated in the control of actin polymerization. Their localization in anterior pituitary suggests that rhoB could control the association of synaptic-like microvesicles and plasma membrane, and that rhoA/rhoC could play a role in secretory granule exocytosis; these two pathways being involved in cytoskeleton protein reorganisation in response to extracellular signals.
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Affiliation(s)
- D Cussac
- I.C.N.E. UMR 9941 CNRS Institut Jean Roche Faculté de Médecine Nord, Marseille, France
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3
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Suzuki T, Okumura-Noji K, Nishida E. ERK2-type mitogen-activated protein kinase (MAPK) and its substrates in postsynaptic density fractions from the rat brain. Neurosci Res 1995; 22:277-85. [PMID: 7478291 DOI: 10.1016/0168-0102(95)00902-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mitogen-activated protein kinase (MAPK) and MAPK kinase (MAPKK) were detected by Western blotting in the synaptic fraction prepared from the rat brain. There were two bands immunoreactive to the anti-MAPK antiserum in the soluble, P2, synaptosome, and synaptic plasma membrane fractions. These immunoreactive bands possibly corresponded to extracellular signal-regulated kinase (ERK) 1 and 2 (Boulton et al., 1991b), respectively. Only ERK2 was detected in the postsynaptic density (PSD) fraction. We then surveyed MAPK substrates in the synaptic fractions using purified Xenopus MAPK (ERK2-type MAPK), and found a number of MAPK substrates unique to the PSD fraction. Thus, ERK2 is present in the synapse, especially at the postsynaptic site, and it may play a role(s) in synaptic function via the phosphorylation of synapse-specific substrates. Developmental changes in ERK2 also supported its role in the synapse.
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Affiliation(s)
- T Suzuki
- Department of Biochemistry, Nagoya City University Medical School, Japan
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4
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Urayama O, Murakoshi T, Ikawa Y. K rev-1 protein is abundantly expressed in the rat spinal cord. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1243:446-52. [PMID: 7727520 DOI: 10.1016/0304-4165(94)00174-v] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The K rev-1 gene, which was originally identified as a dominantly functioning tumor suppressor gene inducing a flat revertant of a v-K-ras-transformed NIH 3T3 cell line, was abundantly expressed in the mammalian brain [Kitayama et al. (1989) Cell 56, 77-84]. To investigate where K rev-1 and its family ras proteins are distributed in the central nervous system, we isolated the membrane fractions from several regions of the brain and spinal cord of rats by subcellular fractionation and analyzed those proteins by immunoblot analysis with the specific monoclonal antibodies, K rev-1 protein was detected at the highest level in the spinal cord among areas of the central nervous system which included cerebral cortex, cerebellum, hippocampus, and olfactory bulb. On the other hand, ras proteins were found at similar levels in these regions. Within the spinal cord, K rev-1 and ras proteins were detected at a comparable level in the ventral and dorsal parts, while they were much less in the dorsal root ganglion than in the spinal cord. They showed the differential expression during early postnatal development: K rev-1 protein increased and ras proteins were at relatively high levels. When K rev-1 and ras proteins were examined in synaptosomes from the lumbar spinal cord of newborn rats, most of them were detected not in the synaptic vesicles but in the synaptic plasma membranes. K rev-1 protein as well as ras proteins might be involved in neuronal functions in the spinal cord such as sensory processing and motor control.
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Affiliation(s)
- O Urayama
- Department of Laboratory Medicine, Akita University School of Medicine, Japan
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5
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Stettler O, Moya KL, Zahraoui A, Tavitian B. Developmental changes in the localization of the synaptic vesicle protein rab3A in rat brain. Neuroscience 1994; 62:587-600. [PMID: 7830899 DOI: 10.1016/0306-4522(94)90391-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Rab3A is a protein associated with the membrane of synaptic vesicles and is involved in the control of the targeting or docking of these vesicles at the presynaptic membrane for the release of neurotransmitters. Here, we have examined the expression and localization of this protein during the development of the rat brain. Relative to total protein, the concentration of rab3A greatly increased during brain development. Both the intracellular localization of the protein and its cerebral distribution showed an age-dependent shift. In contrast to other synaptic vesicle proteins, rab3A was heavily concentrated in cell bodies when immature neurons were migrating and during early differentiation. Later, the protein disappeared from perikarya and had a diffuse distribution in the neuropil, indicating a redistribution to nerve terminals, its exclusive localization in the adult. In the developing somatosensory cortex, rab3A delimited the modular organization of the barrels well after the afferents have arrived but just around the time that mature synaptic activity has been observed. In the hippocampus, rab3A defined a novel "blob-like" organization of the mossy fibre terminals and its appearance in terminal fields closely preceded the known onset of long-term potentiation. The appearance of rab3A in specific terminal fields during the period of increased physiological activity suggests that this small GTP-binding protein may be an important late element in the establishment of the mature characteristics of the presynaptic terminal.
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Affiliation(s)
- O Stettler
- INSERM U 334, Service hospitalier Frédéric Joliot, Commissariat à l'Energie Atomique, Orsay, France
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6
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Jalink K, van Corven EJ, Hengeveld T, Morii N, Narumiya S, Moolenaar WH. Inhibition of lysophosphatidate- and thrombin-induced neurite retraction and neuronal cell rounding by ADP ribosylation of the small GTP-binding protein Rho. J Cell Biol 1994; 126:801-10. [PMID: 8045941 PMCID: PMC2120149 DOI: 10.1083/jcb.126.3.801] [Citation(s) in RCA: 529] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Addition of the bioactive phospholipid lysophosphatidic acid (LPA) or a thrombin receptor-activating peptide (TRP) to serum-starved N1E-115 or NG108-15 neuronal cells causes rapid growth cone collapse, neurite retraction, and transient rounding of the cell body. These shape changes appear to be driven by receptor-mediated contraction of the cortical actomyosin system independent of classic second messengers. Treatment of the cells with Clostridium botulinum C3 exoenzyme, which ADP-ribosylates and thereby inactivates the Rho small GTP-binding protein, inhibits LPA- and TRP-induced force generation and subsequent shape changes. C3 also inhibits LPA-induced neurite retraction in PC12 cells. Biochemical analysis reveals that the ADP-ribosylated substrate is RhoA. Prolonged C3 treatment of cells maintained in 10% serum induces the phenotype of serum-starved cells, with initial cell flattening being followed by neurite outgrowth; such C3-differentiated cells fail to retract their neurites in response to agonists. We conclude that RhoA is essential for receptor-mediated force generation and ensuing neurite retraction in N1E-115 and PC12 cells, and that inactivation of RhoA by ADP-ribosylation abolishes actomyosin contractility and promotes neurite outgrowth.
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Affiliation(s)
- K Jalink
- Division of Cellular Biochemistry, The Netherlands Cancer Institute, Amsterdam
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7
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Stettler O, Zahraoui A, Moya KL, Tavitian B. Expression of the small GTP-binding protein Rab3A in the adult rat brain. Mol Cell Neurosci 1992; 3:497-507. [DOI: 10.1016/1044-7431(92)90062-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/1992] [Indexed: 10/26/2022] Open
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8
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Abstract
The three mammalian ras proteins associated specifically with the plasma membrane and this is essential for their biological activity. Two signals encoded within the extreme COOH terminus of the proteins specify this cellular localization; a CAAX box in combination with either a polybasic domain (p21K-rasB) or a palmitoylation site (p21Ha-ras and p21N-ras). All members of the ras-like and rho-like subfamilies of the ras superfamily of small GTP-binding proteins also have CAAX boxes with potential second site sequences resembling either p21K-rasB or P21N-ras/Ha-ras. However it is not at all clear that they are each located at the plasma membrane, and in fact one of the ras-like proteins, rap1, has been localized to the Golgi (Beranger et al., 1991). None of the mammalian rho-like subfamily has yet been localized. Three forms (A, B, and C) of p21rho, the prototype of this family are known; the COOH termini of p21rhoA and p21rhoC resemble p21K-rasB with a polybasic domain, whereas p21rhoB resembles p21N-ras/Ha-ras with two cysteine residues as potential palmitoylation sites. Despite this similarity to the p21ras proteins, rho proteins have been purified from both particulate and cytosolic fractions of a variety of tissues. In order to localize definitively the three rho proteins we have used an epitope tagging approach coupled to microinjection of living cells. We show that a small fraction of all three proteins is localized to the plasma membrane but the majority of p21rhoA and p21rhoC is cytosolic whereas p21rhoB is associated with early endosomes and a pre-lysosomal compartment. Along with the results obtained with chimeric molecules using heterologous proteins attached to rho COOH termini, this suggests that the p21rho proteins cycle on and off the plasma membrane and this may have important implications for their biological function.
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Affiliation(s)
- P Adamson
- Section of Cell and Molecular Biology, Chester Beatty Laboratories, Institute of Cancer Research, London, United Kingdom
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9
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Moya KL, Tavitian B, Zahraoui A, Tavitian A. Localization of the ras-like rab3A protein in the adult rat brain. Brain Res 1992; 590:118-27. [PMID: 1330210 DOI: 10.1016/0006-8993(92)91087-u] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Rab3A is a small GTP-binding synaptic vesicle protein, shown to dissociate from synaptic vesicle membranes upon depolarization-induced exocytosis. Using an antiserum raised against rab3A, we found that the antigen was localized to the neuropil of specific brain regions, but was not present in major fiber tracts or most cell bodies. For example, the neuropil of several thalamic nuclei (i.e., dorsal lateral geniculate nucleus, lateral posterior nucleus, ventroposterior nucleus), cerebral cortex, upper layers of the superior colliculus and matrix zones of the neostriatum, were strongly immunoreactive, while the anterior commissure, corpus callosum, optic tract and internal capsule were devoid of staining. The hippocampus, regions of cerebral cortex and the cerebellum exhibited striking laminar distributions of rab3A immunoreactivity. In the hippocampus, dark staining was observed in the stratum oriens, stratum radiatum and molecular layer of the dentate gyrus, while the pyramidal, stratum lacunosum moleculare and dentate granule layers were not stained. In cerebellum the molecular layer and to a lesser extent, the underlying granule cell layer showed enhanced immunoreactivity. Seven days after excitotoxic lesions of the cerebral cortex, rab3A immunoreactivity was diminished in the mirror locus in the contralateral cortical hemisphere and in certain thalamic nuclei ipsilateral to the injection site. These results show that rab3A is localized to a number of specific regions. Its absence from other areas suggests that this synaptic vesicle protein is not universal to all neuronal terminals and pathways. In addition, our lesion studies indicate that for some brain regions, much of the antigen originates in cortical neurons and is distributed within specific axonal projections.
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Affiliation(s)
- K L Moya
- INSERM U334, SHFJ, CEA, Orsay, France
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10
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Takai Y, Kaibuchi K, Kikuchi A, Kawata M. Small GTP-binding proteins. INTERNATIONAL REVIEW OF CYTOLOGY 1992; 133:187-230. [PMID: 1577587 DOI: 10.1016/s0074-7696(08)61861-6] [Citation(s) in RCA: 275] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Y Takai
- Department of Biochemistry, Kobe University School of Medicine, Japan
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11
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Basson MD, Goldenring JR, Tang LH, Lewis JJ, Padfield P, Jamieson JD, Modlin IM. Redistribution of 23 kDa tubulovesicle-associated GTP-binding proteins during parietal cell stimulation. Biochem J 1991; 279 ( Pt 1):43-8. [PMID: 1656941 PMCID: PMC1151544 DOI: 10.1042/bj2790043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small GTP-binding proteins are important regulators of intracellular traffic. The presence of several small GTP-binding proteins was documented in subfractions of rabbit parietal cells. Upon maximal stimulation of the cells with a combination of histamine and forskolin, one 23 kDa GTP-binding band was observed to decrease in a 50,000 g membrane fraction while increasing in 4000 g membranes. The 23 kDa band resolved into one major and two minor species on two-dimensional gels. GTP-binding species of 23 kDa, 24 kDa and 25 kDa were present in purified preparations of tubulovesicles. The three isoelectric species of the 23 kDa proteins observed in parietal cell 50,000 g microsomes were enriched in tubulovesicle preparations. None of the tubulovesicle-associated GTP-binding proteins were substrates for ADP-ribosylation by a preparation of botulinum D toxin. These results indicate that tubulovesicles contain discrete small GTP-binding proteins which redistribute during parietal cell stimulation.
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Affiliation(s)
- M D Basson
- Department of Surgery, Yale University School of Medicine, New Haven, CT 06510
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12
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The ras-related gene rhoB is an immediate-early gene inducible by v-Fps, epidermal growth factor, and platelet-derived growth factor in rat fibroblasts. Mol Cell Biol 1991. [PMID: 1710770 DOI: 10.1128/mcb.11.7.3682] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A set of genes is rapidly inducible when quiescent fibroblasts are stimulated by growth factors or by the activation of temperature-sensitive retroviral protein-tyrosine kinases. Most of these so-called immediate-early genes were cloned by differential cDNA hybridization. DNA sequence analysis identified many of them as putative members of the growth factor or of the transcription factor gene family, suggesting a role in signal transmission during the G0-to-G1 transition. In this study, we identified one of the genes that are rapidly inducible by the retroviral protein-tyrosine kinases v-Src and v-Fps of Rous sarcoma virus and Fujinami sarcoma virus, respectively, as the rhoB gene, a member of the ras gene superfamily whose products are GTP-binding proteins, rhoB is transiently activated at the transcriptional level by v-Fps and by epidermal growth factor. Its labile RNA is inducible in the presence of cycloheximide but not of actinomycin D. rhoB is strongly induced by epidermal growth factor and by platelet-derived growth factor both in subconfluent, serum-starved and in density-arrested Rat-2 fibroblasts. Fetal calf serum is a poor inducer, particularly in density-arrested cells, and phorbol esters do not increase rhoB expression at all. These data suggest that rhoB is inducible by protein-tyrosine kinases through a pathway not involving the activation of protein kinase C. Neither the closely related rhoC and rhoA genes nor the distantly related c-H-ras gene is rapidly inducible by mitogens. Thus, rhoB is the first known member of the small GTP-binding proteins among the immediate-early genes.
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13
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Katayama M, Kawata M, Yoshida Y, Horiuchi H, Yamamoto T, Matsuura Y, Takai Y. The posttranslationally modified C-terminal structure of bovine aortic smooth muscle rhoA p21. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98947-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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14
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Jähner D, Hunter T. The ras-related gene rhoB is an immediate-early gene inducible by v-Fps, epidermal growth factor, and platelet-derived growth factor in rat fibroblasts. Mol Cell Biol 1991; 11:3682-90. [PMID: 1710770 PMCID: PMC361128 DOI: 10.1128/mcb.11.7.3682-3690.1991] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A set of genes is rapidly inducible when quiescent fibroblasts are stimulated by growth factors or by the activation of temperature-sensitive retroviral protein-tyrosine kinases. Most of these so-called immediate-early genes were cloned by differential cDNA hybridization. DNA sequence analysis identified many of them as putative members of the growth factor or of the transcription factor gene family, suggesting a role in signal transmission during the G0-to-G1 transition. In this study, we identified one of the genes that are rapidly inducible by the retroviral protein-tyrosine kinases v-Src and v-Fps of Rous sarcoma virus and Fujinami sarcoma virus, respectively, as the rhoB gene, a member of the ras gene superfamily whose products are GTP-binding proteins, rhoB is transiently activated at the transcriptional level by v-Fps and by epidermal growth factor. Its labile RNA is inducible in the presence of cycloheximide but not of actinomycin D. rhoB is strongly induced by epidermal growth factor and by platelet-derived growth factor both in subconfluent, serum-starved and in density-arrested Rat-2 fibroblasts. Fetal calf serum is a poor inducer, particularly in density-arrested cells, and phorbol esters do not increase rhoB expression at all. These data suggest that rhoB is inducible by protein-tyrosine kinases through a pathway not involving the activation of protein kinase C. Neither the closely related rhoC and rhoA genes nor the distantly related c-H-ras gene is rapidly inducible by mitogens. Thus, rhoB is the first known member of the small GTP-binding proteins among the immediate-early genes.
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Affiliation(s)
- D Jähner
- Molecular Biology and Virology Laboratory, Salk Institute, San Diego, California 92186
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15
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A mammalian inhibitory GDP/GTP exchange protein (GDP dissociation inhibitor) for smg p25A is active on the yeast SEC4 protein. Mol Cell Biol 1991. [PMID: 1901952 DOI: 10.1128/mcb.11.5.2909] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Evidence is accumulating that smg p25A, a small GTP-binding protein, may be involved in the regulated secretory processes of mammalian cells. The SEC4 protein is known to be required for constitutive secretion in yeast cells. We show here that the mammalian GDP dissociation inhibitor (GDI), which was identified by its action on smg p25A, is active on the yeast SEC4 protein in inhibiting the GDP/GTP exchange reaction and is capable of forming a complex with the GDP-bound form of the SEC4 protein but not with the GTP-bound form. These results together with our previous findings that smg p25A GDI is found in mammalian cells with both regulated and constitutive secretion types suggest that smg p25A GDI plays a role in both regulated and constitutive secretory processes, although smg p25A itself may be involved only in regulated secretory processes. These results also suggest that a GDI for the SEC4 protein is present in yeast cells.
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16
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Sasaki T, Kaibuchi K, Kabcenell AK, Novick PJ, Takai Y. A mammalian inhibitory GDP/GTP exchange protein (GDP dissociation inhibitor) for smg p25A is active on the yeast SEC4 protein. Mol Cell Biol 1991; 11:2909-12. [PMID: 1901952 PMCID: PMC360085 DOI: 10.1128/mcb.11.5.2909-2912.1991] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Evidence is accumulating that smg p25A, a small GTP-binding protein, may be involved in the regulated secretory processes of mammalian cells. The SEC4 protein is known to be required for constitutive secretion in yeast cells. We show here that the mammalian GDP dissociation inhibitor (GDI), which was identified by its action on smg p25A, is active on the yeast SEC4 protein in inhibiting the GDP/GTP exchange reaction and is capable of forming a complex with the GDP-bound form of the SEC4 protein but not with the GTP-bound form. These results together with our previous findings that smg p25A GDI is found in mammalian cells with both regulated and constitutive secretion types suggest that smg p25A GDI plays a role in both regulated and constitutive secretory processes, although smg p25A itself may be involved only in regulated secretory processes. These results also suggest that a GDI for the SEC4 protein is present in yeast cells.
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Affiliation(s)
- T Sasaki
- Department of Biochemistry, Kobe University School of Medicine, Japan
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17
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Sahyoun N, McDonald OB, Farrell F, Lapetina EG. Phosphorylation of a Ras-related GTP-binding protein, Rap-1b, by a neuronal Ca2+/calmodulin-dependent protein kinase, CaM kinase Gr. Proc Natl Acad Sci U S A 1991; 88:2643-7. [PMID: 1901412 PMCID: PMC51294 DOI: 10.1073/pnas.88.7.2643] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A neuron-specific Ca2+/calmodulin-dependent protein kinase, CaM kinase Gr, phosphorylates selectively a Ras-related GTP-binding protein (Rap-1b) that is enriched in brain tissue. The phosphorylation reaction achieves a stoichiometry of about 1 and involves a serine residue near the carboxyl terminus of the substrate. Both CaM kinase Gr and cAMP-dependent protein kinase, but not CaM kinase II, phosphorylate identical or contiguous serine residues in Rap-1b. The rate of phosphorylation of Rap-1b by CaM kinase Gr is enhanced following autophosphorylation of the protein kinase. Other low molecular weight GTP-binding proteins belonging to the Ras superfamily, including Rab-3A, Rap-2b, and c-Ha-ras p21, are not phosphorylated by CaM kinase Gr. The phosphorylation of Rap-1b itself can be reversed by an endogenous brain phosphoprotein phosphatase. These observations provide a potential connection between a neuronal Ca2(+)-signaling pathway and a specific low molecular weight GTP-binding protein that may regulate neuronal transmembrane signaling, vesicle transport, or neurotransmitter release.
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Affiliation(s)
- N Sahyoun
- Wellcome Research Laboratories, Research Triangle Park, NC 27709
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18
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Role of the C-terminal region of smg p25A in its interaction with membranes and the GDP/GTP exchange protein. Mol Cell Biol 1991. [PMID: 1899908 DOI: 10.1128/mcb.11.3.1438] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
smg p25A is a ras p21-like small GTP-binding protein which is implicated in the regulated secretory processes. We have recently found that bovine brain smg p25A is geranylgeranylated at its C-terminal region. In this study, we examined the function(s) of the C-terminal region of smg p25A. Limited proteolysis of bovine brain smg p25A with Achromobacter protease I produced an N-terminal fragment and a C-terminal tail. The Mrs of intact smg p25A, the N-terminal fragment, and the C-terminal tail were estimated to be about 24,000, 20,000, and less than 2,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal fragment contained the consensus amino acid sequences for GDP/GTP-binding and GTPase activities and showed these activities with kinetic properties similar to those of the intact protein but did not bind to plasma membranes or phosphatidylserine-linked Affigel under conditions in which the intact protein bound to them. The C-terminal tail neither contained the consensus amino acid sequences for GDP/GTP-binding and GTPase activities nor bound to plasma membranes or phosphatidylserine-linked Affigel. The GDP/GTP exchange protein specific for smg p25A, named GDP dissociation inhibitor (GDI), made a complex with the GDP-bound form of the intact smg p25A at a molar ratio of 1:1 and thereby inhibited its GDP/GTP exchange reaction but neither made a complex with the N-terminal fragment or the C-terminal tail nor affected the GDP/GTP exchange reaction of the N-terminal fragment. We expressed smg p25A in Escherichia coli and purified it to near homogeneity. This bacterial protein was not geranylgeranylated. Bacterial smg p25A did not bind to plasma membranes or phosphatidylserine-linked Affigel. smg p25A GDI neither made a complex with bacterial smg p25A nor affected its GDP/GTP exchange reaction. These results suggest that the N-terminal region of smg p25A has GDP/GTP-binding and GTPase activities but lacks the ability to interact with membranes and smg p25A GDI, that the C-terminal region of smg p25A plays important roles in its interaction with membranes and smg p25A GDI, and that some modifications of the C-terminal region, such as geranylgeranylation, which are absent in bacterial smg p25A, are important for these interactions.
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19
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Araki S, Kaibuchi K, Sasaki T, Hata Y, Takai Y. Role of the C-terminal region of smg p25A in its interaction with membranes and the GDP/GTP exchange protein. Mol Cell Biol 1991; 11:1438-47. [PMID: 1899908 PMCID: PMC369420 DOI: 10.1128/mcb.11.3.1438-1447.1991] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
smg p25A is a ras p21-like small GTP-binding protein which is implicated in the regulated secretory processes. We have recently found that bovine brain smg p25A is geranylgeranylated at its C-terminal region. In this study, we examined the function(s) of the C-terminal region of smg p25A. Limited proteolysis of bovine brain smg p25A with Achromobacter protease I produced an N-terminal fragment and a C-terminal tail. The Mrs of intact smg p25A, the N-terminal fragment, and the C-terminal tail were estimated to be about 24,000, 20,000, and less than 2,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal fragment contained the consensus amino acid sequences for GDP/GTP-binding and GTPase activities and showed these activities with kinetic properties similar to those of the intact protein but did not bind to plasma membranes or phosphatidylserine-linked Affigel under conditions in which the intact protein bound to them. The C-terminal tail neither contained the consensus amino acid sequences for GDP/GTP-binding and GTPase activities nor bound to plasma membranes or phosphatidylserine-linked Affigel. The GDP/GTP exchange protein specific for smg p25A, named GDP dissociation inhibitor (GDI), made a complex with the GDP-bound form of the intact smg p25A at a molar ratio of 1:1 and thereby inhibited its GDP/GTP exchange reaction but neither made a complex with the N-terminal fragment or the C-terminal tail nor affected the GDP/GTP exchange reaction of the N-terminal fragment. We expressed smg p25A in Escherichia coli and purified it to near homogeneity. This bacterial protein was not geranylgeranylated. Bacterial smg p25A did not bind to plasma membranes or phosphatidylserine-linked Affigel. smg p25A GDI neither made a complex with bacterial smg p25A nor affected its GDP/GTP exchange reaction. These results suggest that the N-terminal region of smg p25A has GDP/GTP-binding and GTPase activities but lacks the ability to interact with membranes and smg p25A GDI, that the C-terminal region of smg p25A plays important roles in its interaction with membranes and smg p25A GDI, and that some modifications of the C-terminal region, such as geranylgeranylation, which are absent in bacterial smg p25A, are important for these interactions.
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Affiliation(s)
- S Araki
- Department of Biochemistry, Kobe University School of Medicine, Japan
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20
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Shimizu K, Kaibuchi K, Nonaka H, Yamamoto J, Takai Y. Tissue and subcellular distributions of an inhibitory GDP/GTP exchange protein (GDI) for the rho proteins by use of its specific antibody. Biochem Biophys Res Commun 1991; 175:199-206. [PMID: 1900152 DOI: 10.1016/s0006-291x(05)81220-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have recently purified from bovine brain cytosol to near homogeneity a GDP/GTP exchange protein for the rho proteins, named rho GDI, that inhibits the dissociation of GDP from and the subsequent binding of GTP to the rho proteins. In the present study, we made a monoclonal antibody against rho GDI and studied its tissue distribution in rat and its subcellular distribution in rat cerebrum by use of this antibody. rho GDI was found in most rat tissues as described for the rho proteins. In rat cerebrum, rho GDI was mostly found in the cytosol of neuron body and synaptosome. In synaptosome, it was mainly found in the synaptic cytosol.
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Affiliation(s)
- K Shimizu
- Department of Biochemistry, Kobe University School of Medicine, Japan
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21
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Motoike T, Sano K, Tsuneishi S, Nakamura H, Takai Y. Expression of smg p25A, a ras p21-like small GTP-binding protein, during postnatal development of rat cerebellum. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1990; 57:279-89. [PMID: 2127384 DOI: 10.1016/0165-3806(90)90054-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Changes in expression and localization of smg p25A, a ras p21-like small GTP-binding protein, in developing rat brain were analyzed in comparison with those of synaptophysin, a well-known synaptic vesicle-specific protein. The smg 25A mRNA was detected in whole brain of rat fetus at 14 days of gestation and its level was increased along with the age and reached the maximum level at postnatal day (P) 20. In postnatal cerebellum, the smg25A mRNA level was also increased age-dependently and the maximum level was observed at P30. Immunoblot analysis with an anti-smg p25A monoclonal antibody (MAb SG-11-7) and an anti-synaptophysin monoclonal antibody (SY 38) showed that expression of both smg p25A and synaptophysin was increased age-dependently in postnatal rat cerebellum. By immunofluorescent cytochemical study with the anti-smg p25A antibody, bright fluorescence was observed in the molecular layer of cerebellum and it was increased in accordance with the cerebellar development. In early postnatal cerebellum, the perikarya of Purkinje cells and the white matter were brightly stained with the antibody, but the fluorescence of these portions was faint in adult cerebellum. The anti-synaptophysin monoclonal antibody also stained the molecular layer of cerebellum but the perikarya of Purkinje cells and the white matter had only a weak immunoreactivity with the antibody irrespective of the age. These results indicate that smg p25A is predominantly present in the nerve terminals and that its amount is increased along with the development of postnatal rat cerebellum. Our results also suggest that smg p25A and synaptophysin have the different kinetics of synthesis, transport, and/or turnover in developing rat cerebellum.
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Affiliation(s)
- T Motoike
- Department of Pediatrics, Kobe University School of Medicine, Japan
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22
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Bourne HR, Sanders DA, McCormick F. The GTPase superfamily: a conserved switch for diverse cell functions. Nature 1990; 348:125-32. [PMID: 2122258 DOI: 10.1038/348125a0] [Citation(s) in RCA: 1803] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Proteins that bind and hydrolyse GTP are being discovered at a rapidly increasing rate. Each of these many GTPases acts as a molecular switch whose 'on' and 'off' states are triggered by binding and hydrolysis of GTP. Conserved structure and mechanism in myriad versions of the switch--in bacteria, yeast, flies and vertebrates--suggest that all derive from a single primordial protein, repeatedly modified in the course of evolution to perform a dazzling variety of functions.
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Affiliation(s)
- H R Bourne
- Department of Pharmacology, University of California, San Francisco 94143
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23
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Molecular cloning and characterization of a novel type of regulatory protein (GDI) for smg p25A, a ras p21-like GTP-binding protein. Mol Cell Biol 1990. [PMID: 2115118 DOI: 10.1128/mcb.10.8.4116] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently purified to near homogeneity a novel type of regulatory protein for smg p25A, a ras p21-like GTP-binding protein, from bovine brain cytosol. This regulatory protein, named smg p25A GDP dissociation inhibitor (GDI), regulates the GDP-GTP exchange reaction of smg p25A by inhibiting dissociation of GDP from and subsequent binding of GTP to it. In the present studies, we isolated and sequenced the cDNA of smg p25A GDI from a bovine brain cDNA library by using an oligonucleotide probe designed from the partial amino acid sequence of purified smg p25A GDI. The cDNA has an open reading frame that encodes a protein of 447 amino acids with a calculated Mr of 50,565. This Mr is similar to those of the purified smg p25A GDI estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sucrose density gradient ultracentrifugation, which are about 54,000 and 65,000, respectively. The isolated cDNA is expressed in Escherichia coli, and the encoded protein exhibits GDI activity. smg p25A GDI is hydrophilic overall, except for one hydrophobic region near the N terminus. smg p25A GDI shares low amino acid sequence homology with the Saccharomyces cerevisiae CDC25-encoded protein, which has been suggested to serve as a factor that regulates the GDP-GTP exchange reaction of the yeast RAS2-encoded protein, but not with the beta gamma subunits of GTP-binding proteins having an alpha beta gamma subunit structure, such as Gs and Gi. The smg p25A GDI mRNA was present in various tissues, including not only tissues in which smg p25A was detectable but also tissues in which it was not detectable. This fact has raised the possibility that smg p25A GDI interacts with another G protein in tissues in which smg p25A is absent.
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24
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Matsui Y, Kikuchi A, Araki S, Hata Y, Kondo J, Teranishi Y, Takai Y. Molecular cloning and characterization of a novel type of regulatory protein (GDI) for smg p25A, a ras p21-like GTP-binding protein. Mol Cell Biol 1990; 10:4116-22. [PMID: 2115118 PMCID: PMC360933 DOI: 10.1128/mcb.10.8.4116-4122.1990] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We recently purified to near homogeneity a novel type of regulatory protein for smg p25A, a ras p21-like GTP-binding protein, from bovine brain cytosol. This regulatory protein, named smg p25A GDP dissociation inhibitor (GDI), regulates the GDP-GTP exchange reaction of smg p25A by inhibiting dissociation of GDP from and subsequent binding of GTP to it. In the present studies, we isolated and sequenced the cDNA of smg p25A GDI from a bovine brain cDNA library by using an oligonucleotide probe designed from the partial amino acid sequence of purified smg p25A GDI. The cDNA has an open reading frame that encodes a protein of 447 amino acids with a calculated Mr of 50,565. This Mr is similar to those of the purified smg p25A GDI estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sucrose density gradient ultracentrifugation, which are about 54,000 and 65,000, respectively. The isolated cDNA is expressed in Escherichia coli, and the encoded protein exhibits GDI activity. smg p25A GDI is hydrophilic overall, except for one hydrophobic region near the N terminus. smg p25A GDI shares low amino acid sequence homology with the Saccharomyces cerevisiae CDC25-encoded protein, which has been suggested to serve as a factor that regulates the GDP-GTP exchange reaction of the yeast RAS2-encoded protein, but not with the beta gamma subunits of GTP-binding proteins having an alpha beta gamma subunit structure, such as Gs and Gi. The smg p25A GDI mRNA was present in various tissues, including not only tissues in which smg p25A was detectable but also tissues in which it was not detectable. This fact has raised the possibility that smg p25A GDI interacts with another G protein in tissues in which smg p25A is absent.
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Affiliation(s)
- Y Matsui
- Research Center, Mitsubishi Kasei Corporation, Yokohama, Japan
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25
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Regulation of reversible binding of smg p25A, a ras p21-like GTP-binding protein, to synaptic plasma membranes and vesicles by its specific regulatory protein, GDP dissociation inhibitor. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38260-2] [Citation(s) in RCA: 192] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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26
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Yamamoto J, Kikuchi A, Ueda T, Ohga N, Takai Y. A GTPase-activating protein for rhoB p20, a ras p21-like GTP-binding protein--partial purification, characterization and subcellular distribution in rat brain. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1990; 8:105-11. [PMID: 2169565 DOI: 10.1016/0169-328x(90)90054-h] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A protein stimulating the GTPase activity of rhoB p20, a ras p21-like GTP-binding protein (G protein), was partially purified from the cytosol fraction of bovine brain. This protein, designated as rhoB p20 GTPase-activating protein (GAP), did not stimulate the GTPase activity of other ras p21/ras p21-like G proteins including c-Ha-ras p21, smg p21 and smg p25A. The activities of c-Ha-ras p21 GAP and smg p21 GAP were also detected in the cytosol fraction of bovine brain and rhoB p20 GAP was separated from these GAPs. The activity of rhoB p20 GAP was eliminated by tryptic digestion or boiling. The Mr value of rhoB p20 GAP was estimated to be 150-200 x 10(3) and 37 x 10(3) by gel filtration and sucrose density gradient ultracentrifugation, respectively. These results indicate that there is rhoB p20 GAP in addition to c-Ha-ras p21 GAP and smg p21 GAP in bovine brain. In rat brain, about 50% of rhoB p20 GAP was found with the highest specific activity in the P2 fraction containing myelin, synaptosomes and mitochondria. In the P2 fraction, about 30% of rhoB p20 GAP was found in the P2C fraction containing mainly synaptosomes. rhoB p20 GAP was detected in the cytosol and particulate fractions of not only rat brain but also other rat tissues.
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Affiliation(s)
- J Yamamoto
- Department of Biochemistry, Kobe University School of Medicine, Japan
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27
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Mizoguchi A, Kim S, Ueda T, Kikuchi A, Yorifuji H, Hirokawa N, Takai Y. Localization and subcellular distribution of smg p25A, a ras p21-like GTP-binding protein, in rat brain. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38480-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Tissue and subcellular distributions of the smg-21/rap1/Krev-1 proteins which are partly distinct from those of c-ras p21s. Mol Cell Biol 1990. [PMID: 2111441 DOI: 10.1128/mcb.10.6.2645] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have made a specific antiserum recognizing both smg p21A (the rap1A/Krev-1 protein) and -B (the rap1B protein), ras p21-like GTP-binding proteins having the same putative effector domain as ras p21s and have used this antiserum to study the tissue and subcellular distributions of smg p21s by immunoblot and immunocytochemical analyses. By immunoblot analysis, smg p21s were detected in various rat tissues and at the highest level in brain. By light microscopic immunocytochemical analysis, smg p21s were also detected in various rat tissues. Particularly, smg p21s in brain were found abundantly in the cytoplasmic region of most types of neuronal cell bodies and moderately in neuropil, whereas c-ras p21s were found more abundantly in neuropil than in the cytoplasmic region of most types of neuronal cell bodies. smg p21s in testis were found in spermatogenic cells, in which c-ras p21s were not significantly detected. By subcellular fractionation analysis of cerebrum, smg p21s were detected in all of the particulate fractions but not in the cytosol fraction. Among the particulate fractions, approximately 70% of smg p21s was recovered with the highest specific content in the fraction containing mainly synaptosomes, mitochondria, and myelin. In further fractionation of this fraction, approximately 40% of smg p21s was recovered in each of the synaptosome fraction and the mitochondrial fraction. This subcellular distribution of smg p21s in cerebrum was partly distinct from that of c-ras p21s, which were mainly recovered in the synaptosome and microsome fractions but present at very low levels in the mitochondrial fraction. These tissue and subcellular distributions of smg p 21s together with the fact that smg p21s have the same putative effector domain as ras p21s exert their own specific actions in addition to the actions similar or antagonistic to those of c-ras p21s.
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29
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Ohmori T, Takeyama Y, Ueda T, Hiroyoshi M, Nakanishi H, Ohyanagi H, Saitoh Y, Takai Y. Purification and characterization of a novel GTP-binding protein with a Mr value of 24,000 from rat liver. Biochem Biophys Res Commun 1990; 169:816-23. [PMID: 2162674 DOI: 10.1016/0006-291x(90)90404-b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
About 15% of the total GTP-binding proteins (G proteins) of rat liver homogenate was found in the microsomes-Golgi complex fraction. From this fraction, we purified to near homogeneity and characterized a G protein with a Mr value of 24,000 (24K G). 24K G specifically bound guanosine 5'-(3-Q-thio) triphosphate (GTP gamma S), GTP and GDP with a Kd value for GTP gamma S of about 30 nM. 24K G bound maximally about 0.7 mol of GTP gamma S/mol of protein. 24K G hydrolyzed GTP to liberate Pi with a turnover number of about 0.008 min-1. 24K G was not copurified with the beta gamma subunit of heterotrimeric G proteins. The partial amino acid sequences of 24K G revealed that this protein was a novel small G protein.
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Affiliation(s)
- T Ohmori
- Department of Surgery, Kobe University School of Medicine, Japan
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30
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Kim S, Mizoguchi A, Kikuchi A, Takai Y. Tissue and subcellular distributions of the smg-21/rap1/Krev-1 proteins which are partly distinct from those of c-ras p21s. Mol Cell Biol 1990; 10:2645-52. [PMID: 2111441 PMCID: PMC360623 DOI: 10.1128/mcb.10.6.2645-2652.1990] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have made a specific antiserum recognizing both smg p21A (the rap1A/Krev-1 protein) and -B (the rap1B protein), ras p21-like GTP-binding proteins having the same putative effector domain as ras p21s and have used this antiserum to study the tissue and subcellular distributions of smg p21s by immunoblot and immunocytochemical analyses. By immunoblot analysis, smg p21s were detected in various rat tissues and at the highest level in brain. By light microscopic immunocytochemical analysis, smg p21s were also detected in various rat tissues. Particularly, smg p21s in brain were found abundantly in the cytoplasmic region of most types of neuronal cell bodies and moderately in neuropil, whereas c-ras p21s were found more abundantly in neuropil than in the cytoplasmic region of most types of neuronal cell bodies. smg p21s in testis were found in spermatogenic cells, in which c-ras p21s were not significantly detected. By subcellular fractionation analysis of cerebrum, smg p21s were detected in all of the particulate fractions but not in the cytosol fraction. Among the particulate fractions, approximately 70% of smg p21s was recovered with the highest specific content in the fraction containing mainly synaptosomes, mitochondria, and myelin. In further fractionation of this fraction, approximately 40% of smg p21s was recovered in each of the synaptosome fraction and the mitochondrial fraction. This subcellular distribution of smg p21s in cerebrum was partly distinct from that of c-ras p21s, which were mainly recovered in the synaptosome and microsome fractions but present at very low levels in the mitochondrial fraction. These tissue and subcellular distributions of smg p 21s together with the fact that smg p21s have the same putative effector domain as ras p21s exert their own specific actions in addition to the actions similar or antagonistic to those of c-ras p21s.
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Affiliation(s)
- S Kim
- Department of Biochemistry, Kobe University School of Medicine, Japan
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31
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Ueda T, Kikuchi A, Ohga N, Yamamoto J, Takai Y. Purification and characterization from bovine brain cytosol of a novel regulatory protein inhibiting the dissociation of GDP from and the subsequent binding of GTP to rhoB p20, a ras p21-like GTP-binding protein. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38859-3] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Fujioka H, Kikuchi A, Yoshida Y, Kuroda S, Takai Y. A small GTP-binding protein (G protein) recognized by smg p25A GDP dissociation inhibitor (GDI) in human platelet membranes and GDI for this small G protein in human platelet cytosol. Biochem Biophys Res Commun 1990; 168:1244-52. [PMID: 2111992 DOI: 10.1016/0006-291x(90)91162-l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have recently purified from bovine brain cytosol a novel type of regulatory protein for smg p25A, named smg p25A GDP dissociation inhibitor (GDI), that regulates the GDP/GTP exchange reaction of smg p25A by inhibiting the dissociation of GDP from and thereby the subsequent binding of GTP to it. This smg p25A GDI is inactive for other ras p21/ras p21-like small GTP-binding proteins (G proteins) including c-Ha-ras p21, smg p21, rhoA p21 and rhoB p20. In human platelet membranes, smg p25A was not detected but a G protein with an apparent Mr value of 24,000 (24KG) was recognized by smg p25A GDI and the dissociation of GDP from and the binding of GTP to 24KG were inhibited by smg p25A GDI. The doses of smg p25A GDI necessary for these activities for both 24KG and smg p25A were the same. This 24KG was not recognized by an anti-smg p25A monoclonal antibody. The GDI activity for human platelet 24KG and smg p25A was detected in human platelet cytosol. This human platelet GDI was recognized by an anti-smg p25A GDI polyclonal antibody. These results indicate that there is a 24KG-24KG GDI system similar to a smg p25A-smg p25A GDI system in human platelets.
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Affiliation(s)
- H Fujioka
- Department of Biochemistry, Kobe University School of Medicine, Japan
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33
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Hoshijima M, Kondo J, Kikuchi A, Yamamoto K, Takai Y. Purification and characterization from bovine brain membranes of a GTP-binding protein with a Mr of 21,000, ADP-ribosylated by an ADP-ribosyltransferase contaminated in botulinum toxin type C1--identification as the rhoA gene product. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1990; 7:9-16. [PMID: 2153899 DOI: 10.1016/0169-328x(90)90067-n] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have previously shown that there are multiple GTP-binding proteins (G proteins) with Mr values of about 20,000 in bovine brain membranes and identified one G protein with a Mr of 20,000 as the rho gene product. We have also shown that this rho gene product is ADP-ribosylated by an ADP-ribosyltransferase contaminated in botulinum toxin type C1. In the present studies, we have purified another G protein with a Mr of about 21,000 to near homogeneity from bovine brain membranes by several column chromatographies and identified it as the rhoA gene product. Further analysis of the amino acid sequence of the G protein, which we have purified and identified as the rho gene product previously, has revealed that this G protein is the rhoB gene product. The rhoA gene product binds maximally about 0.9 mol of [35S]guanosine 5'-(3-O-thio) triphosphate (GTP gamma S)/mol of protein with a K d value of about 20 nM. [35S]GTP gamma S-binding to the rhoA gene product is inhibited by pretreatment with N-ethylmaleimide. The rhoA gene product hydrolyzes GTP to liberate Pi with a turnover number of about 0.01 min-1. Moreover, the rhoA gene product is ADP-ribosylated by an ADP-ribosyltransferase contaminated in botulinum toxin type Cl. About 0.3 mol of ADP-ribose is maximally incorporated into 1 mol of the rhoA gene product. The ADP ribosylation of the rhoA gene product does not affect its GTP gamma S-binding or GTPase activity. These properties of the rhoA gene product are similar those of the rhoB gene product described previously. These results together with the earlier observations indicate that there are at least two rho gene products (rhoA, B) among three members of the rho gene family (rhoA, B, C) in bovine brain membranes and that both of them are ADP-ribosylated by an ADP-ribosyltransferase contaminated in botulinum toxin type C1.
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Affiliation(s)
- M Hoshijima
- Department of Biochemistry, Kobe University School of Medicine, Japan
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