XB-ART-27618EMBO J March 1, 1988; 7 (3): 633-8.
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Binding to membrane proteins within the endoplasmic reticulum cannot explain the retention of the glucose-regulated protein GRP78 in Xenopus oocytes.
We have studied the compartmentation and movement of the rat 78-kd glucose-regulated protein (GRP78) and other secretory and membrane proteins in Xenopus oocytes. Full length GRP78, normally found in the lumen of rat endoplasmic reticulum (ER), is localized to a membraneous compartment in oocytes and is not secreted. A truncated GRP78 lacking the C-terminal (KDEL) ER retention signal is secreted, although at a slow rate. When the synthesis of radioactive GRP78 is confined to a polar (animal or vegetal) region of the oocyte and the subsequent movement across the oocyte monitored, we find that both full-length and truncated GRP78 move at similar rates and only slightly slower than a secretory protein, chick ovalbumin. In contrast, a plasma membrane protein (influenza haemagglutinin) and two ER membrane proteins (rotavirus VP10 and a mutant haemagglutinin) remained confined to their site of synthesis. We conclude that the retention of GRP78 in the ER is not due to its tight binding to a membrane-bound receptor.
PubMed ID: 3396535
PMC ID: PMC454367
Article link: EMBO J
Species referenced: Xenopus laevis
Genes referenced: hspa5
References [+] :
Armstrong, Expression of coronavirus E1 and rotavirus VP10 membrane proteins from synthetic RNA. 1988, Pubmed, Xenbase