Constitutive apical secretion of an 80-kD sulfated glycoprotein complex in the polarized epithelial Madin-Darby canine kidney cell line.
Open Access
- 1 December 1987
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 105 (6), 2735-2743
- https://doi.org/10.1083/jcb.105.6.2735
Abstract
The biosynthesis, processing, and apical secretion of a group of polypeptides (Kondor-Koch, C., R. Bravo, S. D. Fuller, D. Cutler, and H. Garoff. 1985. Cell. 43:297-306) are studied in MDCK cells using a specific polyclonal antiserum. These polypeptides are synthesized as a precursor protein which has an apparent Mr of 65,000 in its high mannose form. This precursor is converted into a protein with an apparent Mr of 80,000 containing complex carbohydrates and sulfate. After intracellular cleavage of the 80-kD protein, the 35-45-kD subunits are secreted as an 80-kD glycoprotein complex (gp 80) linked together by disulfide bonds. Secretion of the protein complex occurs by a constitutive pathway at the apical surface of the epithelial monolayer. Since the immediate post-translational precursor, the 65-kD protein, is hydrophilic in nature as shown by its partitioning behavior in a phase-separated Triton X-114 solution, gp 80 is segregated into the apical exocytotic pathway as a soluble molecule. The proteolytic maturation of gp 80 is blocked in the presence of chloroquine and its secretion is retarded. The 80-kD precursor is released at the apical cell surface, demonstrating that proteolytic processing is not necessary for the apical secretion of this protein. If N-glycosylation is inhibited by tunicamycin treatment the protein is secreted in equal amounts at both cell surfaces, indicating a role of the carbohydrate moieties in the vectorial transport of this protein.Keywords
This publication has 43 references indexed in Scilit:
- Conversion of proinsulin to insulin occurs coordinately with acidification of maturing secretory vesicles.The Journal of cell biology, 1986
- Intracellular sorting and polarized cell surface delivery of (Na+,K+)ATPase, an endogenous component of MDCK cell basolateral plasma membranesCell, 1986
- Polymeric immunoglobulin receptor expressed in MDCK cells transcytoses IgACell, 1986
- Intracellular sorting and basolateral appearance of the G protein of vesicular stomatitis virus in Madin-Darby canine kidney cells.The Journal of cell biology, 1985
- Vesicular stomatitis virus infects and matures only through the basolateral surface of the polarized epithelial cell line, MDCKCell, 1984
- Reduced temperature prevents transfer of a membrane glycoprotein to the cell surface but does not prevent terminal glycosylationCell, 1983
- Hepatoma secretory proteins migrate from rough endoplasmic reticulum to Golgi at characteristic ratesNature, 1983
- Chloroquine diverts ACTH from a regulated to a constitutive secretory pathway in AtT-20 cellsNature, 1983
- Passage of viral membrane proteins through the Golgi complexJournal of Molecular Biology, 1981
- Intracellular Aspects of the Process of Protein SynthesisScience, 1975