Confocal immunofluorescence microscopy reveals that both XMAPs are associated with spindle MTs during mitosis. XMAP 230 also associates with interphase MTs, including the novel network of subcortical MTs required for formation of the D-V axis in early Xenopus embryos. Their distinct distributions and differing effects on MT assembly in vitro suggest that XMAPs play very different roles in regulating MT assembly and organization in vivo . Recent evidence indicates that XMAP215 is the Xenopus homolog of ch-TOGp, a protein over expressed in several human tumors. We are using a number of techniques, including confocal microscopy, immuno-electron microscopy, in vitro MT and spindle assembly, microinjection of specific antibodies, and molecular techniques, to probe the function of these XMAP215 proteins during oogenesis and development.
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Phosphorylation by CDK1 regulates XMAP215 function in vitro . XMAP230 is required for normal spindle assembly in vivo and in vitro. J. Cell Sci. XMAP230 is required for the organization of cortical microtubules and patterning of the dorsoventral axis in fertilized Xenopus eggs. XMAP230 is required for the assembly and organization of acetylated microtubules in Xenopus oocytes and eggs.