Regulation of the interaction of actin filaments with microtubule-associated protein 2 by calmodulin-dependent protein kinase II.
Phosphorylation of microtubule-associated protein 2 (MAP 2) by Ca2+-, calmodulin-dependent protein kinase II (protein kinase II) inhibited the actin filament cross-linking activity of MAP 2. This inhibition required the presence of ATP, Mg2+, Ca2+ and calmodulin. The minimal concentration of MAP 2 required for gel formation of actin filaments was increased with increasing amounts of phosphate incorporated into MAP 2, and the phosphorylated MAP 2, into which 10.3 mol of phosphate/mol of protein had been incorporated, did not cause actin filaments to gel under the experimental conditions used. The phosphorylation of MAP 2 by Ca2+-, phospholipid-dependent protein kinase (protein kinase C) and cAMP-dependent protein kinase also inhibited the actin filament cross-linking activity of MAP 2. The extent and rate of phosphorylation of MAP 2 by protein kinase II were higher than those of the phosphorylation by protein kinase C and cAMP-dependent protein kinase. The interaction of actin filaments with MAP 2 was inhibited more by the actions of protein kinase II and protein kinase C than by cAMP-dependent protein kinase. The actin filament cross-linking activity of MAP 2 phosphorylated either by protein kinase II, cAMP-dependent protein kinase or protein kinase C was retrieved when phosphorylated MAP 2 was treated by protein phosphatase. These results indicate that the interaction of actin filaments with MAP 2 is regulated by the phosphorylation-dephosphorylation of MAP 2.
Yamauchi
T
T
Department of Biochemistry, Asahikawa Medical College, Japan.
Fujisawa
H
H
D000199:Actins / Q000378:metabolism*; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002540:Cerebral Cortex / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats
D000199:Actins; D008869:Microtubule-Associated Proteins; D011494:Protein Kinases; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases