title: Biosynthesis of the epidermal growth factor receptor in cultured human cells.
abstract: A 160,000 mol wt precursor of the epidermal growth factor (EGF) receptor has been identified in human A-431 carcinoma cells and skin fibroblasts. The presence of one discrete precursor band indicates the presence of a slow processing step. We have determined that this slow processing step involves the conversion of high mannose N-linked oligosaccharides on the receptor precursor to primarily complex oligosaccharides on the mature form of the receptor. This is shown by 1) the presence of fucose, a characteristic terminal sugar of complex oligosaccharides, in only the mature receptor and by 2) the susceptibility of the precursor to digestion with endoglycosidase H, which cleaves high mannose N-linked oligosaccharides, but not complex oligosaccharides from glycoproteins. The precursor to mature receptor transition half-time is 1.7 h in A-431 cells. This long transition half-time causes an accumulation of approximately 7.2 X 10(5) precursor molecules per cell (approximately 12% of the total population of EGF receptors). The net quantity of mature EGF receptors, but not of receptor precursors, is reduced when EGF is added to the culture medium of A-431 cells. The presence of EGF in the growth medium also decreases electrophoretic migration (as a result of increased phosphate incorporation) of the mature receptor, but not that of the precursor. The EGF-insensitive state of the precursor is most likely due to its intracellular location.
authors.forename: C M
authors.initials: CM
authors.lastname: Stoscheck
authors.forename: A M
authors.initials: AM
authors.lastname: Soderquist
authors.forename: G
authors.initials: G
authors.lastname: Carpenter
mesh_terms: D002277:Carcinoma / Q000378:metabolism; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008970:Molecular Weight; D011498:Protein Precursors / Q000032:analysis; D011956:Receptors, Cell Surface / Q000096:biosynthesis*; D012867:Skin / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D011498:Protein Precursors; D011956:Receptors, Cell Surface; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D014357:Trypsin