KENBIKYO Vol.51▶No.1 2016
â– Feature Articles: Novel Insights on Transport Systems within and between Cells

Rab6 Functions for Polarized Transports in Drosophila Photoreceptors

Takunori Satoh, Yuri Nakamura and Akiko K. Satoh

Abstract: The cells in animal bodies have multiple plasma membrane domains; this polarized characteristic of the cells is essential for their specific functions. Selective membrane transport pathways play key roles in the construction and maintenance of polarized structures. Drosophila photoreceptor haboring multiple plasma membrane domains is an excellent model of polarized transport. We performed genetic screening and identified a Rab6 null mutant with a rare phenotype characterized by a loss of 2 apical transport pathways with normal basolateral transport. Although Rab6 functions in the Golgi apparatus are well known, its function in polarized transport is unexpected. Here, we found that Rab6 and its regulator, Rich are required for multiple apical transport pathways but not for the basolateral transport pathway. Our findings strongly indicate that the membrane proteins delivered to multiple polarized domains are not sorted simultaneously: basolateral cargos are segregated before the Rab6-dependent process, and cargos going to multiple apical domains are sorted after Rab6-dependent transport from the trans-Golgi network to the Golgi-associated Rab11-positive compartment, which is presumably recycling endosomes. Our finding of the function of Rab6 in polarized transport will elucidate the molecular mechanisms of polarized transport.

Key words: Rab6, photoreceptor, sorting, trans-Golgi network, recycling endosome