Calmodulin binds to a tubulin binding site of the microtubule-associated protein tau |
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Authors: | Rodolfo Padilla Ricardo B Maccioni Jesús Avila |
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Institution: | (1) Centro de Bíologia Molecular, Universidad Autónoma, 28049 Madrid, Spain;(2) International Center for Cancer and Developmental Biology, Casilla, 70111 Santiago 7, Chile;(3) Faculty of Biological Sciences, Catholic University of Chile, Chile, USA |
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Abstract: | 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 a (430–441) and (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 Ca 2+/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. |
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Keywords: | tau protein tubulin binding site calmodulin interaction microtubule assembly |
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