Phosphorylation of microtubule-associated protein 2 at distinct sites by calmodulin-dependent and cyclic-AMP-dependent kinases.
Microtubule-associated protein 2 (MAP2) is an excellent substrate for both cyclic-AMP (cAMP)-dependent and Ca2+/calmodulin-dependent kinases. A recently purified cytosolic Ca2+/calmodulin-dependent kinase (now designated CaM kinase II) phosphorylates MAP2 as a major substrate. We now report that microtubule-associated cAMP-dependent and calmodulin-dependent protein kinases phosphorylate MAP2 on separate sites. Tryptic phosphopeptide digestion and two-dimensional phosphopeptide mapping revealed 11 major peptides phosphorylated by microtubule-associated cAMP-dependent kinase and five major peptide species phosphorylated by calmodulin-dependent kinase. All 11 of the cAMP-dependently phosphorylated peptides were phosphorylated on serine residues, whereas four of five major peptides phosphorylated by the calmodulin-dependent kinase were phosphorylated on threonine. Only one peptide spot phosphorylated by both kinases was indistinguishable by both migration and phosphoamino acid site. The results indicate that cAMP-dependent and calmodulin-dependent kinases may regulate microtubule and cytoskeletal dynamics by phosphorylation of MAP2 at distinct sites.
Goldenring
J R
JR
Vallano
M L
ML
DeLorenzo
R J
RJ
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D003599:Cytoskeleton / Q000378:metabolism; D005260:Female; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D010748:Phosphopeptides / Q000302:isolation & purification / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D008869:Microtubule-Associated Proteins; D010748:Phosphopeptides; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases