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J Cell Biol September 20, 1999; 146 (6): 1265-76.

Regulation of melanosome movement in the cell cycle by reversible association with myosin V.

Rogers SL , Karcher RL , Roland JT , Minin AA , Steffen W , Gelfand VI .

Previously, we have shown that melanosomes of Xenopus laevis melanophores are transported along both microtubules and actin filaments in a coordinated manner, and that myosin V is bound to purified melanosomes (Rogers, S., and V.I. Gelfand. 1998. Curr. Biol. 8:161-164). In the present study, we have demonstrated that myosin V is the actin-based motor responsible for melanosome transport. To examine whether myosin V was regulated in a cell cycle-dependent manner, purified melanosomes were treated with interphase- or metaphase-arrested Xenopus egg extracts and assayed for in vitro motility along Nitella actin filaments. Motility of organelles treated with mitotic extract was found to decrease dramatically, as compared with untreated or interphase extract-treated melanosomes. This mitotic inhibition of motility correlated with the dissociation of myosin V from melanosomes, but the activity of soluble motor remained unaffected. Furthermore, we find that myosin V heavy chain is highly phosphorylated in metaphase extracts versus interphase extracts. We conclude that organelle transport by myosin V is controlled by a cell cycle-regulated association of this motor to organelles, and that this binding is likely regulated by phosphorylation of myosin V during mitosis.

PubMed ID: 10491390
PMC ID: PMC2156116
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: actl6a dnai1 dync1li1 kif3a kif3b klc1 myc tpx2

Article Images: [+] show captions
References [+] :
Adams, Propulsion of organelles isolated from Acanthamoeba along actin filaments by myosin-I. 1986, Pubmed