The molecular regulation of organelle transport in mammalian retinal pigment epithelial cells

Pigment Cell Res. 2006 Apr;19(2):104-11. doi: 10.1111/j.1600-0749.2006.00303.x.


Retinal pigment epithelial cells contain large numbers of melanosomes that can enter the apical processes extending between the outer segments of the overlying photoreceptors. Every day the distal portion of the photoreceptor outer segment is shed and phagocytosed by the retinal pigment epithelial cell. The phagosome is then transported into the cell body and the contents degraded by lysosomal enzymes. This review focuses on recent progress made in the identification of molecules that regulate the transport of melanosomes into the apical processes and the transport of phagosomes into the cell body. Myosin VIIa is a key player in both processes and, at least in the case of melanosome movement, myosin VIIa is recruited to the melanosome via the GTPase, Rab27a. The possible role played by defects in the transport of melanosomes and phagosomes in the development of retinal degenerative diseases is discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Biological Transport / physiology
  • Dyneins / metabolism*
  • Epithelial Cells / metabolism
  • Epithelial Cells / ultrastructure
  • Humans
  • Myosin VIIa
  • Myosins / metabolism*
  • Organelles / metabolism*
  • Organelles / ultrastructure
  • Pigment Epithelium of Eye / metabolism*
  • Pigment Epithelium of Eye / ultrastructure
  • Retinal Degeneration / metabolism*
  • Retinal Degeneration / pathology
  • rab GTP-Binding Proteins / metabolism*
  • rab27 GTP-Binding Proteins


  • MYO7A protein, human
  • Myosin VIIa
  • rab27 GTP-Binding Proteins
  • RAB27A protein, human
  • Myosins
  • Dyneins
  • rab GTP-Binding Proteins