A DI-ACIDIC SIGNAL REQUIRED FOR SELECTIVE EXPORT FROM THE ENDOPLASMIC-RETICULUM

Transport of membrane proteins between intracellular compartments requ ires specific sequences in the protein cytoplasmic domain to direct pa ckaging into vesicle shuttles. A sequence that mediates export from th e endoplasmic reticulum (ER) has proved elusive. A di-acidic signal (A sp-X-Glu, where X represents any amino acid) on the cytoplasmic tail o f vesicular stomatitis virus glycoprotein (VSV-G) and other cargo mole cules was required for efficient recruitment to vesicles mediating exp ort from the ER in baby hamster kidney cells. The existence of such a signal provides evidence that export from the ER occurs through a sele ctive mechanism.