Calcium-dependent neutral protease activity of myelin from bovine spinal cord: evidence for soluble cleavage products of myelin proteins.
Myelin basic protein (MBP) is degraded by a calcium-stimulated protease of myelin. An attempt was made to demonstrate soluble endopeptic cleavage products of this reaction. Myelin from bovine spinal cord was incubated at pH 7.5 with 5 mM CaCl2. Protein patterns were evaluated by quantitative polyacrylamide gel electrophoresis. A selective decrease in MBP of residual myelin was accompanied by trace amounts of insoluble cleavage products only. In contrast, the buffer media contained at least 3 distinct peptides of approximate Mr's between 8 and 11 kDa. They comprised approximately 70% of total soluble protein. There was a striking concentration-dependent effect of millimolar CaCl2 on the release of both undegraded MBP and proteolytic polypeptides along with a novel polypeptide of 15 kDa. The results suggest that calcium ions are strongly affecting the retention of loosely bound myelin protein.
D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology; D002154:Calpain / Q000378:metabolism*; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D009185:Myelin Proteins / Q000032:analysis / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism*
D009185:Myelin Proteins; D010450:Endopeptidases; D002154:Calpain; D002122:Calcium Chloride