151
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Bhalla K, Luo Y, Buchan T, Beachem MA, Guzauskas GF, Ladd S, Bratcher SJ, Schroer RJ, Balsamo J, DuPont BR, Lilien J, Srivastava AK. Alterations in CDH15 and KIRREL3 in patients with mild to severe intellectual disability. Am J Hum Genet 2008; 83:703-13. [PMID: 19012874 DOI: 10.1016/j.ajhg.2008.10.020] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Revised: 10/18/2008] [Accepted: 10/24/2008] [Indexed: 11/17/2022] Open
Abstract
Cell-adhesion molecules play critical roles in brain development, as well as maintaining synaptic structure, function, and plasticity. Here we have found the disruption of two genes encoding putative cell-adhesion molecules, CDH15 (cadherin superfamily) and KIRREL3 (immunoglobulin superfamily), by a chromosomal translocation t(11;16) in a female patient with intellectual disability (ID). We screened coding regions of these two genes in a cohort of patients with ID and controls and identified four nonsynonymous CDH15 variants and three nonsynonymous KIRREL3 variants that appear rare and unique to ID. These variations altered highly conserved residues and were absent in more than 600 unrelated patients with ID and 800 control individuals. Furthermore, in vivo expression studies showed that three of the CDH15 variations adversely altered its ability to mediate cell-cell adhesion. We also show that in neuronal cells, human KIRREL3 colocalizes and interacts with the synaptic scaffolding protein, CASK, recently implicated in X-linked brain malformation and ID. Taken together, our data suggest that alterations in CDH15 and KIRREL3, either alone or in combination with other factors, could play a role in phenotypic expression of ID in some patients.
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MESH Headings
- Cadherins/chemistry
- Cadherins/genetics
- Cadherins/metabolism
- Carrier Proteins/chemistry
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Case-Control Studies
- Cell Adhesion
- Cell Adhesion Molecules, Neuronal/chemistry
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/metabolism
- Chromosomes, Human, Pair 11
- Chromosomes, Human, Pair 16
- Cohort Studies
- Female
- Genetic Variation
- Humans
- Intellectual Disability/genetics
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Middle Aged
- Models, Biological
- Protein Structure, Tertiary
- Translocation, Genetic
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Affiliation(s)
- Kavita Bhalla
- J.C. Self Research Institute of Human Genetics, Greenwood Genetic Center, Greenwood, SC 29646, USA
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152
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Abstract
The brain processes information by transmitting signals at synapses, which connect neurons into vast networks of communicating cells. In these networks, synapses not only transmit signals but also transform and refine them. Neurexins and neuroligins are synaptic cell-adhesion molecules that connect presynaptic and postsynaptic neurons at synapses, mediate signalling across the synapse, and shape the properties of neural networks by specifying synaptic functions. In humans, alterations in genes encoding neurexins or neuroligins have recently been implicated in autism and other cognitive diseases, linking synaptic cell adhesion to cognition and its disorders.
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Affiliation(s)
- Thomas C Südhof
- Neuroscience Institute, Department of Molecular and Cellular Physiology, Stanford University, 1050 Arastradero Road B249, Palo Alto, California 94304, USA.
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153
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Klemmer P, Smit AB, Li KW. Proteomics analysis of immuno-precipitated synaptic protein complexes. J Proteomics 2008; 72:82-90. [PMID: 19022416 DOI: 10.1016/j.jprot.2008.10.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 10/21/2008] [Accepted: 10/23/2008] [Indexed: 11/18/2022]
Abstract
Synapses are key neuronal elements of the brain. They are responsible for transmission, integration, and storage of information between nerve cells. A synapse is considered as the most complex cellular organelle consisting of approximately 1500 of proteins that are interacting in an activity dependent manner. We have initiated a series of immuno-precipitation experiments in conjunction with LC-MS/MS analysis in order to gain better insight into the organization of the synapse. In particular, we focused on proteins that have been implicated previously in the process of neuroplasticity, i.e., the glutamate receptor (GluR2), scaffolding proteins (PSD-95 and CASK), voltage gated potassium (KCNQ2 and Kv4.2) and calcium (CaV beta4) channel subunits, the signalling protein (GIT1) and synaptic vesicle protein (synaptophysin). This study confirms the previous reported protein-protein interactions and furthermore detects novel interactors. In conjunction with the literature reported protein-protein interaction a simple synaptic protein interactome was constructed. This model implicates the potential interaction of distinct protein complexes, and the engagement of single proteins, especially the scaffolding proteins, in multiple protein complexes.
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Affiliation(s)
- P Klemmer
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam,De Boelelaan 1085, 1081 Amsterdam, The Netherlands
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154
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Sanford JL, Mays TA, Varian KD, Wilson JB, Janssen PM, Rafael-Fortney JA. Truncated CASK does not alter skeletal muscle or protein interactors. Muscle Nerve 2008; 38:1116-27. [DOI: 10.1002/mus.20993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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155
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Dresbach T, Nawrotzki R, Kremer T, Schumacher S, Quinones D, Kluska M, Kuhse J, Kirsch J. Molecular architecture of glycinergic synapses. Histochem Cell Biol 2008; 130:617-33. [DOI: 10.1007/s00418-008-0491-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/07/2008] [Indexed: 10/21/2022]
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156
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Ojeh N, Pekovic V, Jahoda C, Määttä A. The MAGUK-family protein CASK is targeted to nuclei of the basal epidermis and controls keratinocyte proliferation. J Cell Sci 2008; 121:2705-17. [DOI: 10.1242/jcs.025643] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Ca2+/calmodulin-associated Ser/Thr kinase (CASK) binds syndecans and other cell-surface proteins through its PDZ domain and has been implicated in synaptic assembly, epithelial polarity and neuronal gene transcription. We show here that CASK regulates proliferation and adhesion of epidermal keratinocytes. CASK is localised in nuclei of basal keratinocytes in newborn rodent skin and developing hair follicles. Induction of differentiation shifts CASK to the cell membrane, whereas in keratinocytes that have been re-stimulated after serum starvation CASK localisation shifts away from membranes upon entry to S phase. Biochemical fractionation demonstrates that CASK has several subnuclear targets and is found in both nucleoplasmic and nucleoskeletal pools. Knockdown of CASK by RNA interference leads to increased proliferation in cultured keratinocytes and in organotypic skin raft cultures. Accelerated cell cycling in CASK knockdown cells is associated with upregulation of Myc and hyperphosphorylation of Rb. Moreover, CASK-knockdown cells show increased hyperproliferative response to KGF and TGFα, and accelerated attachment and spreading to the collagenous matrix. These functions are reflected in wound healing, where CASK is downregulated in migrating and proliferating wound-edge keratinocytes.
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Affiliation(s)
- Nkemcho Ojeh
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
| | - Vanja Pekovic
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
| | - Colin Jahoda
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
| | - Arto Määttä
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
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157
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Hayashi S, Mizuno S, Migita O, Okuyama T, Makita Y, Hata A, Imoto I, Inazawa J. TheCASKgene harbored in a deletion detected by array-CGH as a potential candidate for a gene causative of X-linked dominant mental retardation. Am J Med Genet A 2008; 146A:2145-51. [DOI: 10.1002/ajmg.a.32433] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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158
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Chao HW, Hong CJ, Huang TN, Lin YL, Hsueh YP. SUMOylation of the MAGUK protein CASK regulates dendritic spinogenesis. ACTA ACUST UNITED AC 2008; 182:141-55. [PMID: 18606847 PMCID: PMC2447900 DOI: 10.1083/jcb.200712094] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Membrane-associated guanylate kinase (MAGUK) proteins interact with several synaptogenesis-triggering adhesion molecules. However, direct evidence for the involvement of MAGUK proteins in synapse formation is lacking. In this study, we investigate the function of calcium/calmodulin-dependent serine protein kinase (CASK), a MAGUK protein, in dendritic spine formation by RNA interference. Knockdown of CASK in cultured hippocampal neurons reduces spine density and shrinks dendritic spines. Our analysis of the time course of RNA interference and CASK overexpression experiments further suggests that CASK stabilizes or maintains spine morphology. Experiments using only the CASK PDZ domain or a mutant lacking the protein 4.1–binding site indicate an involvement of CASK in linking transmembrane adhesion molecules and the actin cytoskeleton. We also find that CASK is SUMOylated. Conjugation of small ubiquitin-like modifier 1 (SUMO1) to CASK reduces the interaction between CASK and protein 4.1. Overexpression of a CASK–SUMO1 fusion construct, which mimicks CASK SUMOylation, impairs spine formation. Our study suggests that CASK contributes to spinogenesis and that this is controlled by SUMOylation.
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Affiliation(s)
- Hsu-Wen Chao
- Graduate Institute of Life Science, National Defense Medical Center, National Yang-Ming University, Taipei 11529, Taiwan
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159
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Mukherjee K, Sharma M, Urlaub H, Bourenkov GP, Jahn R, Südhof TC, Wahl MC. CASK Functions as a Mg2+-independent neurexin kinase. Cell 2008; 133:328-39. [PMID: 18423203 DOI: 10.1016/j.cell.2008.02.036] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Revised: 10/30/2007] [Accepted: 02/06/2008] [Indexed: 01/09/2023]
Abstract
CASK is a unique MAGUK protein that contains an N-terminal CaM-kinase domain besides the typical MAGUK domains. The CASK CaM-kinase domain is presumed to be a catalytically inactive pseudokinase because it lacks the canonical DFG motif required for Mg2+ binding that is thought to be indispensable for kinase activity. Here we show, however, that CASK functions as an active protein kinase even without Mg2+ binding. High-resolution crystal structures reveal that the CASK CaM-kinase domain adopts a constitutively active conformation that binds ATP and catalyzes phosphotransfer without Mg2+. The CASK CaM-kinase domain phosphorylates itself and at least one physiological interactor, the synaptic protein neurexin-1, to which CASK is recruited via its PDZ domain. Thus, our data indicate that CASK combines the scaffolding activity of MAGUKs with an unusual kinase activity that phosphorylates substrates recuited by the scaffolding activity. Moreover, our study suggests that other pseudokinases (10% of the kinome) could also be catalytically active.
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Affiliation(s)
- Konark Mukherjee
- Department of Neuroscience, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9111, USA.
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160
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Samuels BA, Hsueh YP, Shu T, Liang H, Tseng HC, Hong CJ, Su SC, Volker J, Neve RL, Yue DT, Tsai LH. Cdk5 promotes synaptogenesis by regulating the subcellular distribution of the MAGUK family member CASK. Neuron 2008; 56:823-37. [PMID: 18054859 PMCID: PMC2151975 DOI: 10.1016/j.neuron.2007.09.035] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 06/08/2007] [Accepted: 09/26/2007] [Indexed: 10/22/2022]
Abstract
Synaptogenesis is a highly regulated process that underlies formation of neural circuitry. Considerable work has demonstrated the capability of some adhesion molecules, such as SynCAM and Neurexins/Neuroligins, to induce synapse formation in vitro. Furthermore, Cdk5 gain of function results in an increased number of synapses in vivo. To gain a better understanding of how Cdk5 might promote synaptogenesis, we investigated potential crosstalk between Cdk5 and the cascade of events mediated by synapse-inducing proteins. One protein recruited to developing terminals by SynCAM and Neurexins/Neuroligins is the MAGUK family member CASK. We found that Cdk5 phosphorylates and regulates CASK distribution to membranes. In the absence of Cdk5-dependent phosphorylation, CASK is not recruited to developing synapses and thus fails to interact with essential presynaptic components. Functional consequences include alterations in calcium influx. Mechanistically, Cdk5 regulates the interaction between CASK and liprin-alpha. These results provide a molecular explanation of how Cdk5 can promote synaptogenesis.
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Affiliation(s)
- Benjamin Adam Samuels
- Howard Hughes Medical Institute, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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161
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Gottmann K. Transsynaptic modulation of the synaptic vesicle cycle by cell-adhesion molecules. J Neurosci Res 2008; 86:223-32. [PMID: 17787017 DOI: 10.1002/jnr.21484] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Delicate control of the synaptic vesicle cycle is required to meet the demands imposed on synaptic transmission by the brain's complex information processing. In addition to intensively analyzed intrinsic regulation, extrinsic modulation of the vesicle cycle by the postsynaptic target neuron has become evident. Recent studies have demonstrated that several families of synaptic cell-adhesion molecules play a significant role in transsynaptic retrograde signaling. Different adhesion systems appear to specifically target distinct steps of the synaptic vesicle cycle. Signaling via classical cadherins regulates the recruitment of synaptic vesicles to the active zone. The neurexin/neuroligin system has been shown to modulate presynaptic release probability. In addition, reverse signaling via the EphB/ephrinB system plays an important role in the activity-dependent induction of long-term potentiation of presynaptic transmitter release. Moreover, the first hints of involvement of cell-adhesion molecules in vesicle endocytosis have been published. A general hypothesis is that specific adhesion systems might use different but parallel transsynaptic signaling pathways able to selectively modulate each step of the synaptic vesicle cycle in a tightly coordinated manner.
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Affiliation(s)
- Kurt Gottmann
- Institut für Neuro- und Sinnesphysiologie, Heinrich-Heine Universität, Düsseldorf, Germany.
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162
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The etiopathogenesis of cleft lip and cleft palate: usefulness and caveats of mouse models. Curr Top Dev Biol 2008; 84:37-138. [PMID: 19186243 DOI: 10.1016/s0070-2153(08)00602-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cleft lip and cleft palate are frequent human congenital malformations with a complex multifactorial etiology. These orofacial clefts can occur as part of a syndrome involving multiple organs or as isolated clefts without other detectable defects. Both forms of clefting constitute a heavy burden to the affected individuals and their next of kin. Human and mouse facial traits are utterly dissimilar. However, embryonic development of the lip and palate are strikingly similar in both species, making the mouse a model of choice to study their normal and abnormal development. Human epidemiological and genetic studies are clearly important for understanding the etiology of lip and palate clefting. However, our current knowledge about the etiopathogenesis of these malformations has mainly been gathered throughout the years from mouse models, including those with mutagen-, teratogen- and targeted mutation-induced clefts as well as from mice with spontaneous clefts. This review provides a comprehensive description of the numerous mouse models for cleft lip and/or cleft palate. Despite a few weak points, these models have revealed a high order of molecular complexity as well as the stringent spatiotemporal regulations and interactions between key factors which govern the development of these orofacial structures.
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163
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Li J, Ashley J, Budnik V, Bhat MA. Crucial role of Drosophila neurexin in proper active zone apposition to postsynaptic densities, synaptic growth, and synaptic transmission. Neuron 2007; 55:741-55. [PMID: 17785181 PMCID: PMC2039911 DOI: 10.1016/j.neuron.2007.08.002] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 07/17/2007] [Accepted: 08/07/2007] [Indexed: 10/22/2022]
Abstract
Neurexins have been proposed to function as major mediators of the coordinated pre- and postsynaptic apposition. However, key evidence for this role in vivo has been lacking, particularly due to gene redundancy. Here, we have obtained null mutations in the single Drosophila neurexin gene (dnrx). dnrx loss of function prevents the normal proliferation of synaptic boutons at glutamatergic neuromuscular junctions, while dnrx gain of function in neurons has the opposite effect. DNRX mostly localizes to the active zone of presynaptic terminals. Conspicuously, dnrx null mutants display striking defects in synaptic ultrastructure, with the presence of detachments between pre- and postsynaptic membranes, abnormally long active zones, and increased number of T bars. These abnormalities result in corresponding alterations in synaptic transmission with reduced quantal content. Together, our results provide compelling evidence for an in vivo role of neurexins in the modulation of synaptic architecture and adhesive interactions between pre- and postsynaptic compartments.
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Affiliation(s)
- Jingjun Li
- Curriculum in Neurobiology, Department of Cell and Molecular Physiology, UNC-Neuroscience Center, Neurodevelopmental Disorders Research Center, University of North Carolina School of Medicine Chapel Hill, NC 27599-7545
| | - James Ashley
- Department of Neurobiology University of Massachusetts Medical School Worcester, MA 01605
| | - Vivian Budnik
- Department of Neurobiology University of Massachusetts Medical School Worcester, MA 01605
| | - Manzoor A. Bhat
- Curriculum in Neurobiology, Department of Cell and Molecular Physiology, UNC-Neuroscience Center, Neurodevelopmental Disorders Research Center, University of North Carolina School of Medicine Chapel Hill, NC 27599-7545
- *To whom correspondence should be addressed: Manzoor Bhat, Ph.D., Neuroscience Research Building, Room #5109, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7545, Tel: (919) 966-1018, Fax: (919) 843-2777,
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164
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Mittelstaedt T, Schoch S. Structure and evolution of RIM-BP genes: identification of a novel family member. Gene 2007; 403:70-9. [PMID: 17855024 DOI: 10.1016/j.gene.2007.08.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 08/03/2007] [Accepted: 08/03/2007] [Indexed: 11/16/2022]
Abstract
RIM-binding proteins (RIM-BPs) were identified as binding partners of the presynaptic active zone proteins RIMs as well as for voltage-gated Ca(2+)-channels. They were suggested to form a functional link between the synaptic-vesicle fusion apparatus and Ca(2+)-channels. Here we show that the RIM-BP gene family diversified in different stages during evolution, but retained their unique domain structure. While invertebrate genomes contain one, and vertebrates include at least two RIM-BPs, we identified an additional gene, RIM-BP3, which is exclusively expressed in mammals. RIM-BP3 is encoded by a single exon of which three copies are present in the human genome. All RIM-BP genes encode proteins with three SH3-domains and two to three fibronectin III repeats. The flanking regions diverge in size and sequence and are alternatively spliced in RIM-BP1 and -2. Quantitative real-time RT-PCR and in situ hybridization analyses revealed overlapping but distinct expression patterns throughout the brain for RIM-BP1 and -2, while RIM-BP3 was detected at high levels outside the nervous system. The modular domain structure of RIM-BPs, their expression pattern and the conservative expansion during evolution shown here support their potential role as important molecular adaptors.
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Affiliation(s)
- Tobias Mittelstaedt
- Department of Neuropathology and Epileptology, University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany
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