title: Dephosphorylation of microtubule-associated protein 2, tau factor, and tubulin by calcineurin.
abstract: Calcineurin dephosphorylated microtubule-associated protein 2 (MAP2) and tau factor phosphorylated by cyclic AMP-dependent and Ca2+, calmodulin-dependent protein kinases from the brain. Tubulin, only phosphorylated by the Ca2+, calmodulin-dependent protein kinase, served as substrate for calcineurin. The concentrations of calmodulin required to give half-maximal activation of calcineurin were 21 and 16 nM with MAP2 and tau factor as substrates, respectively. The Km and Vmax values were in ranges of 1-3 microM and 0.4-1.7 mumol/mg/min, respectively, for MAP2 and tau factor. The Km value for tubulin was in a similar range, but the Vmax value was lower. The peptide map analysis revealed that calcineurin dephosphorylated MAP2 and tau factor universally, but not in a site-specific manner. The autophosphorylated Ca2+, calmodulin-dependent protein kinase was not dephosphorylated by calcineurin. These results suggest that calcineurin plays an important role in the functions of microtubules via dephosphorylation.
authors.forename: S
authors.initials: S
authors.lastname: Goto
authors.forename: H
authors.initials: H
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Fukunaga
authors.forename: T
authors.initials: T
authors.lastname: Iwasa
authors.forename: Y
authors.initials: Y
authors.lastname: Matsukado
authors.forename: E
authors.initials: E
authors.lastname: Miyamoto
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins; D002413:Cations, Divalent; D002417:Cattle; D000242:Cyclic AMP / Q000494:pharmacology; D004258:DNA Polymerase III; D007700:Kinetics; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D002413:Cations, Divalent; D008869:Microtubule-Associated Proteins; D010750:Phosphoproteins; D014157:Transcription Factors; D014404:Tubulin; D000242:Cyclic AMP; D011494:Protein Kinases; C041273:transcription factor tau; D004258:DNA Polymerase III; D010749:Phosphoprotein Phosphatases; D002118:Calcium