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Biomedical subjects

K Mostov

Publications and source records attributed to K Mostov.

24 records · Page 2Linked to original sources
PubMed1991

Sorting of plasma membrane proteins in epithelial cells.

Proteins follow two routes to reach the correct surface (apical or basolateral) of a polarized epithelial cell: direct sorting from the trans-Golgi network and transcytosis from early endosomes. Several signals have been identified recently that control these sorting events, namely a glycosyl-phosphatidylinositol anchor for apical targeting, a 14-residue cytoplasmic segment of the polymeric immunoglobulin receptor for basolateral targeting, and phosphorylation of a Ser residue for transcytosis of this receptor. The machinery involved is still poorly understood.

Animals↗
PubMed1991

The polymeric immunoglobulin receptor.

As a model system to study protein traffic in epithelial cells we have used the polymeric immunoglobulin receptor. This receptor travels first to the basolateral surface where it can bind polymeric IgA or IgM. The receptor is then endocytosed and delivered to endosomes. The receptor is sorted into transcytotic vesicles which are exocytosed at the apical surface. The 103 amino acid cytoplasmic domain of the receptor contains several sorting signals. The 17 residues closest to the membrane are an autonomous signal for basolateral sorting. For endocytosis there are two signals, both of which contain tyrosines. Finally, transcytosis is signaled by serine phosphorylation.

Animals↗
PubMed1990

Vectorial targeting of an endogenous apical membrane sialoglycoprotein and uvomorulin in MDCK cells.

We studied the cell-surface delivery pathways of newly synthesized membrane glycoproteins in MDCK cells and for this purpose we characterized an endogenous apical integral membrane glycoprotein. By combining a pulse-chase protocol with domain-selective cell-surface biotinylation, immune precipitation, and streptavidin-agarose precipitation (Le Bivic et al. 1989. Proc. Natl. Acad. Sci USA. 86:9313-9317), we followed the appearance at the cell surface of a major apical sialoglycoprotein, gp114, a basolateral protein, uvomorulin, and a transcytosing protein, the polyimmunoglobulin receptor (pIg-R). We determined that both gp114 and uvomorulin appeared to be delivered directly to their respective surface, with mistargeting levels of 8 and 2%, respectively. Using the same technique, the pIg-R was first detected on the basolateral domain and then on the apical domain, to be finally released into the apical medium, as described (Mostov, K. E., and D. L. Deitcher. 1986. Cell. 46:613-621). To directly determine whether the gp114 pool present on the basolateral surface was a precursor of the apical gp114, we compared it with the equivalent pIg-R pool, by labeling with sulfo-NHS-SS-biotin, a cleavable, tight junction-impermeable probe, and by following the fraction of this probe that became resistant to basal glutathione and accessible to apical glutathione during incubation at 37 degrees C. We found that, contrary to pIg-R, basolateral gp114 was poorly endocytosed and was not transcytosed to the apical side. These results demonstrate that an endogenous apical integral membrane glycoprotein of Madin-Darby canine kidney cells is sorted intracellularly and is vectorially targeted to the apical surface.

Animals↗