Calpain-mediated proteolysis of microtubule-associated protein 2 (MAP-2) is inhibited by phosphorylation by cAMP-dependent protein kinase, but not by Ca2+/calmodulin-dependent protein kinase II.
The effects of cAMP-dependent protein kinase (cAMP-PK) and Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation on the calpain-mediated degradation of microtubule-associated protein 2 (MAP-2) were studied. Both cAMP-PK and CaMKII readily phosphorylated MAP-2. However, cAMP-PK phosphorylated MAP-2 to a significantly greater extent than did CaMKII (4.5 mol 32P/mol MAP-2 and 1.4 mol 32P/mol MAP-2, respectively). Phosphorylation of MAP-2 by cAMP-PK, but not by CaMKII, significantly inhibited the calpain-induced hydrolysis of MAP-2. These results demonstrate that the phosphorylation of sites on the MAP-2 molecule accessible to cAMP-PK, but not to CaMKII, result in increased resistance to calpain proteolysis.
Johnson
G V
GV
Department of Psychiatry and Behavioral Neurobiology, University of Alabama, Birmingham 35294-0017.
Foley
V G
VG
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002154:Calpain / Q000494:pharmacology*; D002417:Cattle; D003599:Cytoskeleton / Q000378:metabolism; D006868:Hydrolysis; D015151:Immunoblotting; D066298:In Vitro Techniques; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*
D008869:Microtubule-Associated Proteins; D010761:Phosphorus Radioisotopes; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002154:Calpain