SPATIAL STRUCTURE OF ALPHA-,BETA-TUBULINS DERIVED FROM AMINO-ACIDS SEQUENCE ALIGNMENT USING THE METHOD OF 3-DIMENSIONAL PROFILE

The spatial structure of alpha- and beta-tubulins has been obtained on the basis of the known amino acid sequences of proteins by means of t he three-dimensional profile method. Scanning has been performed over all G- and ATP-protein structures available from Protein Data Bank and other local data banks. It has been demonstrated that beta-tubulin is formed by two domains each containing two subdomains: dense and loose . The loops and alpha-helical segments of loose domains form the walls of a GTP ''pocket''. The bottom of the pocket is made up of dense sub domain loops. With the exception of E, N sites, the structures of alph a- and beta-tubulins are very much alike. In the course of tubulin ass embly, the shape of the walls of the beta-tubulin GTP pocket may chang e so that cavities and projections would emerge contributing together to the formation of Mg2+-GTP-activated proton channel.