Open AccessThe Influence of Topology and Glycosylation on the Fate of Heterologous Secretory Proteins Made in Xenopus Oocytes
Author(s) -
COLMAN Alan,
LANE Charles D.,
CRAIG Roger,
BOULTON Anthony,
MOHUN Tim,
MORSER John
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb05072.x
Subject(s) - tunicamycin , endoplasmic reticulum , xenopus , secretory protein , microbiology and biotechnology , secretory pathway , secretion , glycosylation , heterologous , ovalbumin , biology , glycoprotein , messenger rna , translation (biology) , oocyte , biochemistry , gene , embryo , antigen , genetics , unfolded protein response , golgi apparatus
Secretory proteins made in Xenopus laevis oocytes under the direction of heterologous messenger RNA are modified, topologically segregated and exported. Thus the oocyte may serve as a useful surrogate secretory system and we have studied some of the factors governing access to the export pathway. Unglycosylated chicken ovalbumin, synthesized and trapped in the cytosol, is not secreted but glycosylated ovalbumin, found sequestered within vesicles, is exported from oocytes. However, ovalbumin, which is transferred across the endoplasmic reticulum in the presence of tunicamycin and which is indistinguishable by immunoprecipitation, by two‐dimensional gel electrophoresis and by concanavalin‐A—Sepharose binding from the cytosolic form, is still secreted. Guinea‐pig milk proteins and human interferon are also exported from tunicamycin‐treated frog cells. These observations demonstrate that access to the endoplasmic reticulum but not glycosylation is a mandatory intermediate step in secretion. and emphasize the advantages of the oocyte as a surrogate system for the study of the later events in the gene expression pathway.