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J Cell Biol March 4, 2002; 156 (5): 855-65.

Interactions and regulation of molecular motors in Xenopus melanophores.

Gross SP , Tuma MC , Deacon SW , Serpinskaya AS , Reilein AR , Gelfand VI .

Many cellular components are transported using a combination of the actin- and microtubule-based transport systems. However, how these two systems work together to allow well-regulated transport is not clearly understood. We investigate this question in the Xenopus melanophore model system, where three motors, kinesin II, cytoplasmic dynein, and myosin V, drive aggregation or dispersion of pigment organelles called melanosomes. During dispersion, myosin V functions as a "molecular ratchet" to increase outward transport by selectively terminating dynein-driven minus end runs. We show that there is a continual tug-of-war between the actin and microtubule transport systems, but the microtubule motors kinesin II and dynein are likely coordinated. Finally, we find that the transition from dispersion to aggregation increases dynein-mediated motion, decreases myosin V--mediated motion, and does not change kinesin II--dependent motion. Down-regulation of myosin V contributes to aggregation by impairing its ability to effectively compete with movement along microtubules.

PubMed ID: 11864991
PMC ID: PMC2173315
Article link: J Cell Biol
Grant support: [+]
Genes referenced: actl6a dnai1 dync1li1 foxm1 klc1 pnp wars1

Article Images: [+] show captions
References [+] :
Bridgman, Myosin Va movements in normal and dilute-lethal axons provide support for a dual filament motor complex. 1999, Pubmed

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