Monoclonal antibodies localize the exchangeable GTP‐binding site in β‐ and not α‐tubulins

Abstract

A combination of several methods was used to localize the exchangeable GTP-binding site in the alpha/beta-tubulin heterodimer: direct photoaffinity labeling with [alpha-32P]GTP, specific labeling of alpha- and beta-tubulin by tyrosylation and phosphorylation, respectively, and immunoprecipitation with specific monoclonal antibodies. Direct evidence was obtained that GTP binds exclusively to beta- and not alpha-tubulins.