MAP2d promotes bundling and stabilization of both microtubules and microfilaments

Two low molecular weight MAP2 variants have been described, MAP2c and MAP2d. These variants are produced from a single gene by alternative splicing, and in their C-terminal regions contain, respectively, 3 and 4 tandem repeats, some of which are known to be involved in binding to microtubules. Substantial differences in the developmental expression pattern of MAP2c and MAP2d suggest they have different functions in neural cells. In order to investigate the respective roles of these MAP2 variants, we have analyzed the effects of MAP2c and MAP2d expression on microtubule and microfilament organization in transiently transfected cells. Our results show that both variants stabilize microtubules, but only MAP2d stabilizes microfilaments.