Essential function of Drosophila Sec6 in apical exocytosis of epithelial photoreceptor cells.
Polarized exocytosis plays a major role in development and cell differentiation but the mechanisms that target exocytosis to specific membrane domains in animal cells are still poorly understood. We characterized Drosophila Sec6, a component of the exocyst complex that is believed to tether secretory vesicles to specific plasma membrane sites. sec6 mutations cause cell lethality and disrupt plasma membrane growth. In developing photoreceptor cells (PRCs), Sec6 but not Sec5 or Sec8 shows accumulation at adherens junctions. In late PRCs, Sec6, Sec5, and Sec8 colocalize at the rhabdomere, the light sensing subdomain of the apical membrane. PRCs with reduced Sec6 function accumulate secretory vesicles and fail to transport proteins to the rhabdomere, but show normal localization of proteins to the apical stalk membrane and the basolateral membrane. Furthermore, we show that Rab11 forms a complex with Sec5 and that Sec5 interacts with Sec6 suggesting that the exocyst is a Rab11 effector that facilitates protein transport to the apical rhabdomere in Drosophila PRCs.
Beronja
Slobodan
S
Department of Zoology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.
Laprise
Patrick
P
Papoulas
Ophelia
O
Pellikka
Milena
M
Sisson
John
J
Tepass
Ulrich
U
D022005:Adherens Junctions / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D005089:Exocytosis / Q000502:physiology*; D005123:Eye / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D005854:Germ Cells / Q000378:metabolism / Q000648:ultrastructure; D007814:Larva / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport / Q000502:physiology; D022142:Secretory Vesicles / Q000378:metabolism / Q000648:ultrastructure; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000099193:rab11 GTP-Binding Proteins
D029721:Drosophila Proteins; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C502606:Sec6 protein, Drosophila