| Autor: |
Vallano, M L, Goldenring, J R, Buckholz, T M, Larson, R E, DeLorenzo, R J |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; May 1985, Vol. 82 Issue: 10 p3202-3206, 5p |
| Abstrakt: |
Both cAMP- and calmodulin-dependent kinases are proposed regulators of microtubule function by means of their ability to phosphorylate microtubule-associated protein 2(MAP 2). A cAMP-dependent kinase/MAP 2 complex is endogenous to microtubules. In this report, we demonstrate that an endogenous calmodulin-dependent kinase that phosphorylates MAP 2 as a major substrate is also present in microtubules prepared under conditions that preserve kinase activity. This enzyme is identical to a calmodulin-dependent kinase purified previously from rat brain cytosol. A fraction containing calmodulin-dependent kinase and MAP 2 was separated from the cAMP-dependent kinase/MAP 2 complex by gel filtration chromatography of microtubule protein in high ionic strength buffer. All of the recovered calmodulin-dependent kinase activity in microtubules eluted in a single protein peak. The specific activity of the enzyme for MAP 2 was enriched 31-fold in this fraction compared to cytosol. Two-dimensional tryptic phosphopeptide mapping revealed that the endogenous cAMP- and calmodulin-dependent kinases phosphorylated distinct sites on MAP 2. These data demonstrate that both kinases are present in microtubule preparations and that they may differentially regulate MAP 2 function by phosphorylating separate sites on MAP 2. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
