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Purushotham KR, Wang P, Humphreys-Beher MG. Effect of vanadate on amylase secretion and protein tyrosine phosphatase activity in the rat parotid gland. Mol Cell Biochem 1995; 152:87-94. [PMID: 8609916 DOI: 10.1007/bf01076467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Treatment of rat parotid acinar cells with sodium orthovanadate (an inhibitor of protein tyrosine phosphatase) caused a dose-dependent inhibition of phosphatase activity as measured by the hydrolysis of para nitrophenylphosphate (pNPP). Inclusion of 50 microM sodium orthovanadate in in vitro gland cultures prevented the amylase secretion from both untreated control and isoproterenol-stimulated parotid acinar cells. Four different tyrosine-phosphorylated proteins with M(r) 40, 70 and 95 kDa, respectively, were identified in secretory granule preparations from rat parotid glands by immunoblot using a monospecific antibody for phosphotyrosine. An increase in the phosphorylation levels of these phosphoproteins was noted in the presence of 50 microM sodium orthovanadate, suggesting that a protein tyrosine phosphatase (PTPase) is involved in parotid gland protein dephosphorylation reactions. Using antibody to Syp (a PTPase belonging to class 1D), a major fraction of subcellular activity was found to be associated with secretory granule membranes. These results suggest the possible involvement of a PTPase (Syp) in parotid gland secretory mechanisms.
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Affiliation(s)
- K R Purushotham
- Department of Oral Biology, University of Florida, Gainesville 32610, USA
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2
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Takuma T, Ichida T. Catalytic subunit of protein kinase A induces amylase release from streptolysin O-permeabilized parotid acini. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31764-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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3
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Takuma T, Ichida T. Evidence for the involvement of protein phosphorylation in cyclic AMP-mediated amylase exocytosis from parotid acinar cells. FEBS Lett 1994; 340:29-33. [PMID: 7509758 DOI: 10.1016/0014-5793(94)80167-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We evaluated the role of protein phosphorylation in cAMP-mediated amylase exocytosis from parotid acinar cells by using H89, a new protein kinase A (PKA) inhibitor, which is more lipophilic and 25 times more potent than H8. In our previous studies, H8 markedly inhibited protein phosphorylation without decreasing amylase release [Takuma, T. (1988) Biochem. J. 256, 867-871]. These findings were completely reproduced even in the small acini that were prepared by trypsin treatment before collagenase digestion. In the present study, however, H89 strongly inhibited both amylase release and protein phosphorylation in a dose-dependent manner. The inhibitory effect was specific for PKA at least up to 33 microM, since 33 microM H89 did not block amylase release stimulated by PMA. H85, a closely related compound of H89 without inhibitory effect on PKA, did not prevent amylase release or protein phosphorylation at least up to 33 microM. These results suggest that protein phosphorylation by PKA is involved in cAMP-mediated amylase exocytosis. The inhibition of protein phosphorylation by H8 might be insufficient or inadequate for blocking of amylase release.
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Affiliation(s)
- T Takuma
- Department of Oral Biochemistry, School of Dentistry, Higashi Nippon Gakuen University, Hokkaido, Japan
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4
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Spearman TN, Butcher FR. Cellular Regulation of Amylase Secretion by the Parotid Gland. Compr Physiol 1989. [DOI: 10.1002/cphy.cp060304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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Takuma T. Evidence against direct involvement of cyclic AMP-dependent protein phosphorylation in the exocytosis of amylase. Biochem J 1988; 256:867-71. [PMID: 2464999 PMCID: PMC1135496 DOI: 10.1042/bj2560867] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
To examine whether or not the activation of cyclic AMP-dependent protein kinase is coupled to the exocytosis of amylase from rat parotid cells, the effect of protein kinase inhibitors on amylase release and protein phosphorylation was studied. A membrane-permeable inhibitor of cyclic AMP-dependent protein kinase, N-[2-(methylamino)ethyl]-5-isoquinolinesulphonamide (H-8), and peptide fragments of the heat-stable protein kinase inhibitor [PKI-(5-24)-peptide and PKI-(14-24)-amide] strongly inhibited cyclic AMP-dependent protein kinase activity in the cell homogenate. However, H-8 had no inhibitory effect on amylase release from either intact or saponin-permeabilized parotid cells stimulated by isoproterenol or cyclic AMP. Moreover, PKI-(5-24)-peptide and PKI-(14-24)-amide did not inhibit cyclic AMP-evoked amylase release from saponin-permeabilized cells, whereas cyclic AMP-dependent phosphorylations of 21 and 26 kDa proteins in intact or permeabilized cells were markedly inhibited by these inhibitors. These results suggest that cyclic AMP-dependent protein phosphorylation is not directly involved in the exocytosis of amylase regulated by cyclic AMP.
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Affiliation(s)
- T Takuma
- Department of Oral Biochemistry, School of Dentistry, Higashi Nippon Gakuen University, Hokkaido, Japan
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6
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Thiel G, Söling HD. cAMP-dependent protein phosphorylation of membrane proteins in the parotid gland, platelets and liver. Comparison of a 22-kDa phosphoprotein from rat parotid microsomes (protein III) with phosphoproteins of similar molecular size from platelet and liver membranes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 174:601-9. [PMID: 3391174 DOI: 10.1111/j.1432-1033.1988.tb14141.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Stimulation of secretion in exocrine secretory glands leads to the phosphorylation of a 22-kDa membrane protein (protein III) whose function is still unknown [Jahn et al. (1980) Eur. J. Biochem. 112, 345-352; Jahn & Söling (1980) Proc. Natl Acad. Sci. USA 78, 6903-6906]. This report describes the comparison of this protein with phosphorylated membrane proteins of similar molecular mass in platelets and liver. Incubation of platelets with agents which raise the intracellular cAMP concentration results in the phosphorylation of a 22-kDa protein which is also phosphorylated in membrane preparations by endogenous kinases or by exogenous cAMP-dependent protein kinase. It is shown that this protein is distinct from protein III although both proteins have the same molecular mass and are substrates of cAMP-dependent protein kinase. In contrast to platelets, protein III could be demonstrated in liver microsomes. This indicates that the function of protein III is not exclusively linked to the stimulus-secretion coupling in exocrine cells.
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Affiliation(s)
- G Thiel
- Abteilung Klinische Biochemie, Zentrum Innere Medizin, Universität Göttingen
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7
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Thiel G, Schmidt WE, Meyer HE, Söling HD. Purification and characterization of a 22-kDa microsomal protein from rat parotid gland which is phosphorylated following stimulation by agonists involving cAMP as second messenger. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 170:643-51. [PMID: 2828047 DOI: 10.1111/j.1432-1033.1988.tb13746.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Stimulation of secretion in exocrine glands by agonists involving cAMP as second messenger leads to the phosphorylation of the ribosomal protein S6 (protein I) and two other particulate proteins with apparent molecular masses of 24 kDa (protein II) and 22 kDa (protein III) [Jahn, R., Unger, C. & Söling, H. D. (1980) Eur. J. Biochem. 112, 345-352]. This report describes the purification and characterization of protein III. Solubilization studies indicate that protein III is an intrinsic membrane protein. It could be extracted from the endoplasmic reticulum membrane only with Triton X-100, SDS or concentrated formic or acetic acid. The purification of this protein involved extraction of the microsomes with Triton X-100, removal of the detergent by acetone precipitation, extraction of water-soluble proteins, lipids and lipoproteins, and preparative SDS polyacrylamide gel electrophoresis. The protein has a basic pI (greater than 8.7). For determination of the amino acid composition of protein III and for sequencing of its amino-terminal portion, the protein was electroeluted out off the gel, the detergent removed and the protein finally purified by reversed-phase HPLC. Protein III could be phosphorylated in vitro by the catalytic subunit of the cAMP-dependent protein kinase to a degree of approximately 0.14 mol phosphate/mol protein. The only phosphopeptide obtained after in vitro phosphorylation and subsequent tryptic or chymotryptic digestion was identical with the phosphopeptide obtained after stimulation of intact rat parotid gland lobules with isoproterenol. The sequence of this peptide was Lys-Leu-Ser(P)-Glu-Ala-Asp-Asn-Arg. It was confirmed by an analysis of the synthetic peptide following in vitro phosphorylation with cAMP-dependent protein kinase. The first 41 N-terminal residues of protein III were sequenced. So far no sequence homology with other known peptides or proteins could be found.
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Affiliation(s)
- G Thiel
- Abteilung Klinische Biochemie, Zentrum Innere Medizin, Universität Göttingen, Federal Republic of Germany
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8
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Regulation of acetyl-CoA:1-alkyl-sn-glycero-3-phosphocholine O2-acetyltransferase (lyso-PAF-acetyltransferase) in exocrine glands. Evidence for an activation via phosphorylation by calcium/calmodulin-dependent protein kinase. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45627-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Côté A, Doucet JP, Trifaró JM. Phosphorylation and dephosphorylation of chromaffin cell proteins in response to stimulation. Neuroscience 1986; 19:629-45. [PMID: 3774157 DOI: 10.1016/0306-4522(86)90286-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Stimulation of bovine chromaffin cell in culture changed (increased or decreased) the phosphorylation state of several proteins as examined by 32P incorporation. Enhanced phosphorylation of 22 protein bands as well as increased dephosphorylation of a 20.4 kilodaltons protein band was observed when extracts of cultured chromaffin cells stimulated by either acetylcholine or high K+ were subjected to mono-dimensional gel electrophoresis. For several protein bands, the degree of phosphorylation was larger in cells stimulated by acetylcholine than in those challenged by a depolarizing concentration of K+. The most affected phosphoproteins have apparent molecular weights of 14,800, 29,000, 33,000, 57,000 (tubulin subunit), 63,000 (tyrosine hydroxylase subunit) and 94,000. The presence of a low extracellular calcium concentration (0.5 mM Ca2+ plus 15 mM Mg2+) in the incubation medium inhibited (38-100%) the acetylcholine-evoked increases in protein phosphorylation observed previously for 18 protein bands. Trifluoperazine at the concentration required for 50% inhibition of acetylcholine-induced catecholamine release decreases (33-100%) the stimulation-induced phosphorylation in all polypeptides, with the exception of the 14.8 kilodaltons and the dephosphorylated 20.4 kilodaltons components which were not affected. Two-dimensional gel electrophoresis analysis revealed that exposure of chromaffin cells to acetylcholine produced two types of effect on protein phosphorylation: activation of protein kinase activities affecting about 30 polypeptides; activation of protein phosphatase activities resulting in the dephosphorylation of about 40 polypeptides, most of them appearing as minor phosphoproteins, with the exception of the alpha-subunit of pyruvate dehydrogenase and the 20.4 kilodaltons polypeptide. On the basis of their molecular properties (molecular weight and pI) and their abundance in chromaffin cells, the 80 kilodaltons phosphoprotein which focused at pI 4.8 and the 117.5 kilodaltons phosphoprotein which focused at pI 5.0 were identified as chromogranins A and B, respectively. The relationship between acetylcholine-induced protein phosphorylation (or dephosphorylation) and catecholamine secretion was also investigated. The time course of protein phosphorylation (or dephosphorylation) paralleled or preceded [3H]noradrenaline release for 16 phosphoproteins.(ABSTRACT TRUNCATED AT 400 WORDS)
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10
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Nomura H, Izuhara K, Nomura T, Maekawa H, Hagino Y, Kikkawa F, Tachibana M. Cyclic-AMP-dependent protein phosphorylation in the soluble fraction of parotid glands from rats with drug-induced hypothyroidism. Arch Oral Biol 1986; 31:165-9. [PMID: 3013139 DOI: 10.1016/0003-9969(86)90122-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cyclic-AMP-dependent protein kinase from the soluble fraction of parotid glands of hypothyroid rats was partially purified. Its isozyme distribution and kinetic properties were similar to those of euthyroid rats. Electrophoresis of 100 microliters portions at 20 mA per slab revealed that an endogenous protein (mol. wt 68,000) was specifically phosphorylated in hypothyroidism; this protein was not found in euthyroid rats. In the presence of cyclic AMP, there was stimulated phosphorylation of euthyroid-soluble proteins with molecular weights of 115,000, 98,000, 57,000, 50,000, 44,000, 33,000 and 19,000, and of proteins from hypothyroid rats with weights of 115,000, 98,000, 60,000, 50,000, 33,000 and 19,000. Tolbutamide reduced incorporation of 32Pi into soluble proteins from both groups. However, cyclic AMP still induced phosphorylation in euthyroid preparations in the presence of tolbutamide, but its effect was markedly reduced in the hypothyroid state. These differences in endogenous protein phosphorylation may have different effects on amylase release induced by beta-adrenergic stimulation.
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11
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Padel U, Söling HD. Phosphorylation of the ribosomal protein S6 during agonist-induced exocytosis in exocrine glands is catalyzed by calcium-phospholipid-dependent protein kinase (protein kinase C). Experiments with guinea pig parotid glands. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 151:1-10. [PMID: 2992953 DOI: 10.1111/j.1432-1033.1985.tb09061.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ribosomal protein S6 in exocrine cells is phosphorylated during stimulation of exocytosis by cAMP-dependent or calcium-dependent agonists. Under both conditions the same tryptic S6 phosphopeptides (termed A, B, and C) were found [Padel, Kruppa, Jahn & Söling (1983) FEBS Lett. 159, 112-118]. Studies have now been made of the phosphorylation pattern of protein S6 from purified guinea pig parotid ribosomes following in vitro phosphorylation with calmodulin-dependent, phospholipid-dependent, and cAMP-dependent protein kinases. Only the phospholipid-dependent enzyme led to the phosphorylation of peptides A, B, and C, while the cAMP-dependent enzyme phosphorylated only peptides A and C, and the calmodulin-dependent enzyme did not phosphorylate any of the phosphopeptides found in S6 from unstimulated or stimulated intact cells. Guinea pig parotid microsomes contain substantial phospholipid-dependent protein kinase activity. Stimulation of intact parotid glands with tetradecanoylphorbol acetate led to a significant phosphorylation of S6 and a similar tryptic S6 phosphopeptide pattern as seen with carbamoylcholine. It is concluded that activation of phospholipid-dependent protein kinase is responsible for the phosphorylation of protein S6 during stimulation with calcium-dependent and cAMP-dependent secretagogues.
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Söling HD, Padel U, Jahn R, Thiel G, Kricke P, Fest W. Regulation of protein kinases in exocrine secretory cells during agonist-induced exocytosis. ADVANCES IN ENZYME REGULATION 1985; 23:141-56. [PMID: 4072796 DOI: 10.1016/0065-2571(85)90044-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Stimulation of exocytosis in exocrine glands is associated with an increased phosphorylation of several particulate proteins. Irrespective of the type of secretagogue (cAMP-dependent agonists, calcium-dependent agonists, calcium ionophores, phorbol esters) exocytosis is always accompanied by an enhanced phosphorylation of the ribosomal protein S6. It is shown by an analysis of the phosphopeptide pattern of the in vivo and the in vitro phosphorylated S6 protein that the protein kinase responsible for phosphorylation of the S6 protein during enhanced exocytosis is protein kinase C. This is so irrespective of whether the agonist uses cAMP or calcium as second messenger. Experiments with isolated guinea pig parotid gland lobules reveal that not only the acetylcholine analog carbamoylcholine, but also the beta-agonist isoproterenol lead within seconds to an increased formation of diacylglycerol. As diacylglycerol increases the affinity of protein kinase C for calcium this finding would explain why the phosphorylation pattern of the S6 protein reflects activation of protein kinase C also under conditions where (as in the case of stimulation with beta-agonists) cAMP is the primary second messenger. It would further explain why the changes of the phosphorylation of individual histones observed during agonist-induced exocytosis in the parotid gland are quite similar for isoproterenol on one hand and carbamoylcholine on the other. A 22 K protein which becomes phosphorylated only when cAMP serves as second messenger is located in the membrane of the endoplasmic reticulum. A possible relationship of this protein with the calcium transport ATPase of the endoplasmic reticulum is under investigation.
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Spearman TN, Hurley KP, Olivas R, Ulrich RG, Butcher FR. Subcellular location of stimulus-affected endogenous phosphoproteins in the rat parotid gland. J Cell Biol 1984; 99:1354-63. [PMID: 6148346 PMCID: PMC2113334 DOI: 10.1083/jcb.99.4.1354] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Rat parotid minces were labeled with [32P]Pi, stimulated with isoproterenol, homogenized in sucrose, and fractionated on continuous sucrose density gradients. We analyzed the resulting fractions by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiograms were made from the gels. Comparison of fractions from control and isoproterenol-stimulated minces revealed seven phosphoproteins that were affected by isoproterenol. The subcellular location of these proteins was determined by comparing their distribution in the sucrose gradients with that of a number of enzymes that are characteristic of specific organelles. Isoproterenol decreased the phosphorylation of two cytoplasmic proteins (Mr 16,000 and 18,000) and increased the phosphorylation of a third (Mr 14,000). The phosphorylation of two endoplasmic reticulum proteins was increased by isoproterenol (Mr 20,500 and 22,500), as was an Mr 31,000 protein which was probably the S6 ribosomal protein. The phosphorylation of a secretory granule protein (Mr 24,000) was decreased by isoproterenol. We then developed a purification scheme for parotid secretory granules. By using this method, we demonstrated that the phosphorylation of the Mr 24,000 was also decreased by carbamylcholine. Granules purified by this method also contained a small number of other phosphoproteins whose phosphorylation was increased only by isoproterenol. Secretory granule-associated stimulus-affected phosphoproteins were found in the particulate fraction when the granules were hypotonically lysed, and were not extracted from the particulate fraction by washing with 0.6 M KCl.
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Vandermeers A, Vandermeers-Piret MC, Rathe J, Dehaye JP, Winand J, Christophe J. Phosphorylation of 3 particulate proteins in rat pancreatic acini in response to vasoactive intestinal peptide (VIP), secretin and cholecystokinin (CCK-8). Peptides 1984; 5:359-65. [PMID: 6089135 DOI: 10.1016/0196-9781(84)90234-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Rat pancreatic acini were preincubated with 0.4 mM 32Pi for 45 min at 37 degrees C, then exposed for 15 min to VIP, secretin or CCK-8. The incubation was terminated with a stop solution and a fraction rich in mitochondria and zymogen granules was separated from a microsome-rich fraction by differential centrifugation. After heating in the presence of SDS, beta-mercaptoethanol was added and the pattern of equivalent amounts of 32P-labelled proteins was examined by autoradiography of SDS-PAGE gels. VIP, secretin, and CCK-8 stimulated the phosphorylation of a Mr=33 K microsomal protein and that of two proteins of Mr=21 K and Mr=25 K mostly present in a fraction rich in mitochondria and zymogen granules. Stimulations were dose-dependent, the highest stimulant concentrations tested allowing 2- to 3-fold increases of phosphorylation over basal. When 1 nM CCK-8 was used simultaneously with 1 microM VIP, the cyclic AMP levels attained and the pattern of protein phosphorylation were similar to those obtained with VIP alone, and there was a potentiation of amylase secretion; when a supra-maximal 0.1 microM CCK-8 concentration was added, the VIP-induced elevation in cyclic AMP levels and the phosphorylation of the Mr=21 K and Mr=25 K proteins were partially antagonized, and no potentiation any more of secretion occurred. To conclude the in vitro phosphorylation of three particulate proteins (Mr=33 K, 25 K, and 21 K) was similarly increased in rat pancreatic acini in response to secretin and VIP (acting through cyclic AMP) and to CCK-8 (acting mostly through Ca2+).
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Abstract
Chronic reserpinization of mice and rabbits affected parotid gland function; cholinergic and beta-adrenergic-stimulated amylase release were significantly reduced, and cyclic-AMP and cyclic-GMP levels were significantly elevated above control-stimulated levels. Amylase released by dibutyryl-c-AMP was also reduced, suggesting a defect in stimulus-secretion coupling subsequent to c-AMP formation.
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Plewe G, Jahn R, Immelmann A, Bode C, Söling HD. Specific phosphorylation of a protein in calcium accumulating endoplasmic reticulum from rat parotid glands following stimulation by agonists involving cAMP as second messenger. FEBS Lett 1984; 166:96-103. [PMID: 6319193 DOI: 10.1016/0014-5793(84)80052-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Stimulation of secretion in exocrine cells by agonists involving cAMP as second messenger is associated with the phosphorylation of a specific membrane-associated 22.4-kDa protein (protein III) (Jahn et al.). Here it is shown by subcellular fractionation of rat parotid gland lobules that protein III is associated with the endoplasmic reticulum. The submicrosomal fractions containing protein III, also contain the ATP-dependent microsomal calcium pump activity. Protein III in microsomal subfractions can be phosphorylated in vitro with catalytic subunit from cAMP-dependent protein kinase. Phosphorylated protein III contains exclusively P-serine. Protein III can be removed from ER-membranes with acid chloroform-methanol or Triton X-114, but not by high salt wash indicating that it is tightly associated with the membranes. Protein III is smaller than phospholamban and, in contrast to phospholamban, resistant to heating in SDS. A relationship between phosphorylation of protein III and microsomal calcium sequestration is discussed.
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KANAMORI TAKAO, HAYAKAWA TARO, NAGATSU TOSHIHARU. Involvement of β1-adrenergic receptors in regulation of the phosphorylation state of rat parotid gland proteins . Biomed Res 1984. [DOI: 10.2220/biomedres.5.77] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- TAKAO KANAMORI
- Department of Biochemistry, School of Dentistry, Aichi-Gakuin University
| | - TARO HAYAKAWA
- Department of Biochemistry, School of Dentistry, Aichi-Gakuin University
| | - TOSHIHARU NAGATSU
- Laboratory of Cell Physiology, Department of Life Chemistry, Graduate School at Nagatsuta, Tokyo Institute of Technology
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Padel U, Kruppa J, Jahn R, Söling HD. Phosphopeptide patterns of the ribosomal protein S6 following stimulation of guinea pig parotid glands by secretagogues involving either cAMP or calcium as second messenger. FEBS Lett 1983; 159:112-8. [PMID: 6307749 DOI: 10.1016/0014-5793(83)80427-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Stimulation of secretion in exocrine cells is associated with the incorporation of up to 3 to 4 phosphates into the ribosomal protein S6. This occurs with secretagogues involving either cAMP or free calcium as second messenger. An analysis of the phosphorylation pattern of S6 from stimulated guinea pig parotid glands reveals 3 phosphopeptides (termed A,B,C). The phosphopeptide pattern was identical for cAMP- or calcium-mediated stimulation, whereas phosphorylation of the S6 protein in vitro with catalytic subunit of cAMP-dependent protein kinase resulted only in the formation of phosphopeptides A and C. Therefore, secretagogue-mediated phosphorylation is not or not exclusively catalyzed by cAMP-dependent protein kinase even when cAMP is the second messenger.
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Jahn R, Söling HD. Phosphorylation of the ribosomal protein S6 in response to secretagogues in the guinea pig exocrine pancreas, parotid and lacrimal gland. FEBS Lett 1983; 153:71-6. [PMID: 6298009 DOI: 10.1016/0014-5793(83)80121-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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20
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Abstract
A fraction of chromaffin granule membranes contained a number of substrates for endogenous protein kinase activity as well as endogenous phosphatase activity. The major 32P-labelled polypeptide of molecular weight 43,000 appeared to be the alpha-subunit of pyruvate dehydrogenase of residual mitochondria. Several polypeptides showed cyclic AMP stimulation of phosphorylation of which the major polypeptide of molecular weight 59,000 shows half-maximal phosphorylation with 0.49 microM cyclic AMP. The phosphorylation of several other polypeptides is inhibited at high cyclic AMP concentrations. From studies with immunoprecipitation and two-dimensional electrophoresis it was found that alpha- and beta-tubulin and actin were absent from the granule membranes. However 32P labelling of a proportion of the copies of dopamine-beta-hydroxylase was demonstrated. The majority of the substrates for endogenous protein kinase activity are probably on the cytoplasmic side of the granule membrane.
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Jahn R, Padel U, Porsch PH, Söling HD. Adrenocorticotropic hormone and alpha-melanocyte-stimulating hormone induce secretion and protein phosphorylation in the rat lacrimal gland by activation of a cAMP-dependent pathway. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 126:623-9. [PMID: 6291934 DOI: 10.1111/j.1432-1033.1982.tb06826.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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