Specific proteolysis of a brain membrane phosphoprotein (B-50): Effects of calcium and calmodulin
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The membrane bound phosphoprotein B-50 (MW 48K) was isolated from rat brain tissue. The fraction containing the highest endogenous B-50 phosphorylating activity (ASP 57–82%) contains protease activity. In the absence of calcium a time-dependent decrease of the protein B-50 is observed. Under these conditions another phosphoprotein B-60 (MW 46K) appears in the incubation medium. Addition of calcium and/or calmodulin enhances the protease activity whereas the substrate specificity is lost. Results of both isoelectric focussing and peptide mapping indicate that B-50 and B-60 are related proteins. These data support our hypothesis that the recently isolated behaviorally active peptide PIP (MW approx. 1600 D) is the smaller cleavage product of the proteolytic degradation of B-50 to B-60.
KeywordsCalcium Peptide Brain Tissue Substrate Specificity Protease Activity
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- 3.Zwiers, H., Veldhuis, D., Schotman, P., andGispen, W. H. 1976. ACTH, cyclic nucleotides and brain protein phosphorylation in vitro. Neurochem. Res. 1:669–677.Google Scholar
- 4.Zwiers, H., Wiegant, V. M., Schotman, P., andGispen, W. H. 1978. ACTH-induced inhibition of endogenous rat brain protein phosphorylation in vitro: structure-activity. Neurochem. Res. 3:455–463.Google Scholar
- 7.Gispen, W. H., Zwiers, H., Wiegant, V. M., Schotman, P., andWilson, J. E. 1979. The behavioral active neuropeptide ACTH as neurohormone and neuromodulator: The role of cyclic nucleotides and membrane phosphoproteins. Adv. Exp. Med. and Biol. 116:199–224.Google Scholar
- 8.Mahler, H. R., Kleine, L. P., andSorensen, R. G. 1981. Topography of synaptic phosphoprotein. Trans. Am. Soc. Neurochem. 12:213.Google Scholar
- 9.Cleveland, D. W., Fischer, S. G., Kirschner, M. W., andLaemmli, U. K. 1977. Peptide mapping by limited proteolysis in sodium dodecyl sulphate and analysis by gel electrophoresis. J. Biol. Chem. 252:1102–1106.Google Scholar
- 12.Jolles, J., Zwiers, H., van Dongen, C., Schotman, P., Wirtz, K. W. A., andGispen, W. H. 1980. Modulation of brain polyphosphoinositide metabolism by ACTH-sensitive protein phosphorylation. Nature (Lond.) 286:623–625.Google Scholar
- 13.Weber, W., andHilz, H. 1979. Stoichiometry of cAMP binding and limited proteolysis of protein kinase regulatory subunits R I and R II. Biochem. Biophys. Res. Commun. 90:1073–1081.Google Scholar
- 15.Jolles, J., Aloyo, V., andGispen, W. H. 1981. Molecular correlates between pituitary hormones and behavior. Pages 285–316,in Brown, I. R. (ed.), Molecular approaches to neurobiology, Academic Press, New York.Google Scholar