Ca2+– and Calmodulin‐Dependent Phosphorylation of Microtubule‐Associated Protein 2 and t Factor, and Inhibition of Microtubule Assembly

Hideyuki Yamamoto, Kohji Fukunaga, Etsuro Tanaka, Eishichi Miyamoto

Research output: Contribution to journalArticle

144 Citations (Scopus)

Abstract

Abstract: Microtubule‐associated proteins (MAPs) were phosphorylated by a Ca2+– and calmodulin‐dependent protein kinase from rat brain cytosol. The maximal amount of phosphate incorporated into MAPs was 25 nmol of phosphate/mg protein. A Ka value of the enzyme for calmodulin was 57.0 nM, with MAPs as substrates. Among MAPs, MAP2 and t factor were phosphorylated in a Ca2 +‐and calmodulin‐dependent manner. The phosphorylation of MAPs led to an inhibition of microtubule assembly in accordance with its degree. This reaction was dependent on addition of the enzyme, Ca2+, and calmodulin, and had a greater effect on the initial rate of microtubule assembly rather than on the final extent. The critical tubulin concentration for microtubule assembly was unchanged by the MAPs phosphorylation. Therefore assembly and disassembly of brain microtubule are regulated by the Ca2+‐ and calmodulin‐dependent protein kinase that requires only a nanomolar concentration of calmodulin for activation.

Original languageEnglish
Pages (from-to)1119-1125
Number of pages7
JournalJournal of Neurochemistry
Volume41
Issue number4
DOIs
Publication statusPublished - 1983 Apr
Externally publishedYes

Keywords

  • Brain Ca‐ and calmodulin‐dependent protein kinase
  • Microtubule assembly
  • Microtubule‐associated protein 2
  • Microtubule‐associated proteinst
  • Protein phosphorylation
  • factor

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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