Melanosome biogenesis: shedding light on the origin of an obscure organelle.

Melanosomes are specialized intracellular organelles in which melanin pigments are synthesized and stored. The ontogenesis of these morphologically unique organelles, as well as their relationship to "conventional" organelles of the secretory and endocytic pathways, has for decades been a matter of study - and controversy. Recent work by the groups of Michael Marks and Graça Raposo has uncovered the molecular mechanism that results in the formation of the lumenal striations characteristic of melanosome precursor organelles.