Open AccessRegulation of microtubule cold stability by calmodulin-dependent and -independent phosphorylation.
Author(s) -
Didier Job,
Charles T. Rauch,
Edmond H. Fischer,
Robert L. Margolis
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.13.3894
Subject(s) - calmodulin , trifluoperazine , microtubule , phosphorylation , tubulin , biochemistry , chemistry , microtubule associated protein , homogenization (climate) , protein kinase a , protein phosphorylation , microbiology and biotechnology , biophysics , biology , enzyme , biodiversity , ecology
Cold-labile microtubule protein can be rendered cold-stable by addition of a fraction containing a small number of polypeptides that are derived from cold-stable microtubules. These polypeptides can be obtained from purified cold-stable microtubules by passage through a DEAE-cellulose (DE-52) ion exchange column from which they emerge in the first eluate fraction. The stabilizing activity of these proteins is abolished by phosphorylation catalyzed by two types of protein kinases, one dependent on calmodulin and the other independent of that regulatory protein. The calmodulin-dependent reaction appears to phosphorylate mainly two polypeptides, 56 and 72 kilodaltons; the reaction is blocked by trifluoperazine. The calmodulin-independent reaction appears to phosphorylate different cold-stable microtubule-associated proteins. That reaction is observed only in purified material obtained from vigorously homogenized brain tissue. Gently homogenization yields cold-stable microtubules that are responsive only to the calmodulin-dependent protein kinase. A distinguishing feature of the calmodulin-independent reaction is that it does not occur on polypeptides while they are bound to the microtubules.