Melanocytes are cells that control coat and skin color in most animals. Within melanocytes, melanosomes (the pigment-producing organelles) undergo startling rearrangements in response to external cues or due to mutations in transport and targeting machineries.
Melanosomes are clustered together near the center of the cell, but they can be rapidly distributed to the ends of dendritic processes; redistribution involves long-range transport from the center along microtubules and, in the periphery, short-range capture and transport promoted by the molecular motor myosin-Va.
In two studies, Wu et al. examine the molecular basis of peripheral motor-melanosome interaction. On the membrane of the melanosome, a receptor for the myosin-Va motor is formed by the GTP-dependent association of Rab27a (a small GTPase) and melanophilin. These proteins recruit a version of myosin-Va that contains a melanocyte-specific splicing variant encoded by exon F (in the myosin tail region). Similar strategies for specifying motor-vesicle interactions are likely to be found in other vesicle-targeting events. -- SMH
Nature Cell Biol. 10.1038/ncb760; Mol. Biol. Cell 10.1091/mbc.01-12-0595.
