Calmodulin binds to a tubulin binding site of the microtubule-associated protein tau

✍ Scribed by Rodolfo Padilla; Ricardo B. Maccioni; Jesús Avila

• Publisher: Springer
• Year: 1990
• Tongue: English
• Weight: 406 KB
• Volume: 97
• Category: Article
• ISSN: 0300-8177
• DOI: 10.1007/bf00231699

✦ Synopsis

Previous studies have demonstrated that the microtubule-associated proteins MAP-2 and tau interact selectively with common binding domains on tubulin defined by the low-homology segments alpha (430-441) and beta (422-434). It has been also indicated that the synthetic peptide VRSKIGSTENLKHQPGGG corresponding to the first tau repetitive sequence represents a tubulin binding domain on tau. The present studies show that the calcium-binding protein calmodulin interacts with a tubulin binding site on tau defined by the second repetitive sequence VTSKCGSLGNIHHKPGGG. It was shown that both tubulin and calmodulin bind to tau peptide-Sepharose affinity column. Binding of calmodulin occurs in the presence of 1 mM Ca 2+ and it can be eluted from the column with 4 mM EGTA. These findings provide new insights into the regulation of microtubule assembly, since Ca2+/calmodulin inhibition of tubulin polymerization into microtubules could be mediated by the direct binding of calmodulin to tau, thus preventing the interaction of this latter protein with tubulin.