Cell-surface glycosyltransferases in cultured fibroblasts: increased activity and release during serum stimulation of growth.
Proc Natl Acad Sci U S A, 1977/3;74(3):1086-90.
LaMont JT, Gammon MT, Isselbacher KJ
PMID: 191828
Impact factor: 12.779
Abstract
Cell-surface galactosyltransferase was studied in suspensions of intact baby hamster kidney fibroblasts with both endogenous and exogenous glycoprotein acceptors. The cell-surface location of galactosyltransferase was demonstrated in experiments with the enzyme modifier alpha-lactalbumin, which does not enter the cell. The addition of alpha-lactalbumin to the assay medium for galactosyltransferase resulted in accumulation of lactose in the medium but not in the cells. There was no detectable hydrolysis of UDP-galactose to free galactose by these cells, nor did a 100-fold molar excess of free galactose inhibit cell-surface galactosyltransferase. There was a marked increase in specific activity of cell-surface exogenous galactosyltransferase in serum-stimulated as compared to resting fibroblasts. Dividing but not resting fibroblasts released galactosyltransferase, but not sialyl- or fucosyltransferase, in soluble form into the tissue culture medium. The release of galactosyltransferase was greater from virally transformed than from nontransformed fibroblasts.
MeSH terms
Blood; Cell Division; Cell Line; Cell Membrane; Cell Transformation, Neoplastic; Culture Media; Fibroblasts; Galactosyltransferases; Lactalbumin; Lactose; Polyomavirus
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