THE REPETITIVE MICROTUBULE-ASSOCIATED PROTEINS MARP-1 AND MARP-2 OF TRYPANOSOMA-BRUCEI

The microtubular membrane skeleton of Trypanosoma brucei contains two closely related, repetitive, high-molecular-weight microtubule-associa ted proteins, MARP-1 and MARP-2 (MARP for Microtubule-Associated Repet itive Proteins). Their structure is unusual in that they consist of ta ndemly arranged, strongly conserved 38-amino-acid repeat units over al most their entire length of about 320 kDa. Their nonrepetitive N and C ends are comparatively short. The predicted amino acid sequences reve al a gradient of similarity between MARP-1 and MARP-2 which increases from the N-terminus (no significant similarity) through the repeat dom ain (50% similarity) to the C-terminus (94.5% similarity). Transfectio n of mammalian cell lines with recombinant fragments of MARP-2 demonst rate that the nonrepetitive C-terminus of MARP-2 binds specifically to microtubules. This C-terminus does not show sequence similarity with any other microtubule-associated proteins and thus appears to represen t a novel type of microtubule-binding domain. (C) 1994 Academic Press, Inc.