MAPS, MARKS AND MICROTUBULE DYNAMICS

Microtubules (MTs) serve as tracks for cellular transport, and regulat e cell shape and polarity. Rapid transitions between stable and dynami c forms of MTs are central to these processes, This dynamic instabilit y is regulated by a number of cellular factors, including the structur al MT-associated proteins (MAPs), which in turn are regulated by phosp horylation. MT-affinity-regulating kinases (MARKs) are novel mammalian serine/threonine kinases that phosphorylate the tubulin-binding domai n of MAPs and thereby cause their detachment from MTs and increased MT dynamics. Molecular cloning of MARKs revealed a family of four closel y related protein kinases that share homology with genes from the nema tode Caenorhabditis elegans and fission yeast that are involved in the generation of cell shape and polarity, Hence, MARKs might play a role in the regulation of MT stability during morphogenesis.