Functional organization of microtubule-associated protein tau. Identification of regions which affect microtubule growth, nucleation, and bundle formation in vitro.

摘要: Tau protein is a microtubule-associated that almost exclusively expressed in the brain and enriched axon. Determination of tau's sequence has revealed three to four tandem repeats have been shown constitute microtubule binding site. In order study functional organization tau, we prepared series truncated tau fragments using an Escherichia coli expression system. We assayed each fragment's activity promoting growth microtubules nucleating free microtubules. found ability nucleate requires presence additional amino-terminal required for growth. demonstrate carboxyl amino termini differentially affect nucleation. Finally, show vitro bundle formation occurs when tubulin assembled amino- carboxyl-terminally protein, whereas no bundling observed full-length or contain terminus addition repeat domain. conclude although domain promotes microtubules, structural requirements nucleation are more stringent. The differentiation between activities on level makes it possible two be regulated vivo.