Partial structure of a membrane glycopeptide from virus-transformed hamster cells

Abstract

The predominant surface glycopeptide from a clone of baby hamster kidney cells transformed by Rous sarcoma virus (C13/B4), metabolically labeled with L-[14C]fucose, has been characterized for the first time. This glycopeptide represents 19% of the total radioactivity removed by trypsin from the cell surface of the transformed fibroblasts and is more abundant in the transformed cells than in the normal counterpart. Purification of the glycopeptide after digestion with Pronase was by successive chromatography on DEAE-cellulose and Sephadex G-50. The monosaccharide content of the glycopeptide was 42, 127, 138, 114, and 243 nmol of fucose, sialic acid, galatose, mannose, and glucosamine, respectively. A partial structure of the glycopeptide was proposed from the results of sequential enzymatic degradation coupled with gas-liquid chromatographic analysis of the resultant monosaccharides. All of the enzymes used were purified and pretested on natural substrates and found to remove terminal monosaccharides of the correct configuration, quantitatively. The purification and properties of an alpha-L-fucosidase from rat testes were described. All of the radioactivity in the glycopeptide, recovered as fucose, was present at the core and was removed by treatment with this alpha-L-fucosidase. The proposed structure is a triantennary, completely sialylated, complex glycopeptide containing a core region of beta-D-mannose, beta-D-N-acetylglucosamine, and alpha-L-fucose.

Transfection by human oncogenes: Concomitant induction of tumorigenicity and tumor‐associated membrane alterations

“…Analysis of fucosyl-glycopeptides by gel filtration as well as by HPIC and affinity chromatography on Concanavalin A-Sepharose indicated that the glycopeptides derived from the tumor-DNA-induced transfectants were enriched in sialic acid-containing, highly branched glycan structures. These results are in agreement with studies on virally-transformed cells (Warren et al, 1978;Glick, 1979). Our data suggest a close relationship between the presence of rus oncogenes in transfectants and the alteration in fucose-containing membrane glycopeptides.…”

“…The cause of this alteration is thought to reside in the more complex, branched carbohydrate structures, in many cases enriched in terminal sialic acid residues (Ogata et al, 1976;Santer and Glick, 1979;Takasaki et al, 1980;Dorland et al, 1981). The changes in membrane glycopeptides on tumor cells may reflect functional alterations of tumor cells, e.g.…”

The protein component of scrapie-associated fibrils is a glycosylated low molecular weight protein.

“…of deglycosylated SAF-protein to find out whether the differences are solely due to the different content of carbohydrate. The carbohydrate content of the different species would be in agreement with two N-linked carbohydrate chains for the 26-kd species and one N-linked carbohydrate chain for the 24-kd fraction, assuming an average content of five Nacetyl glucosamine residues per N-linked carbohydrate of rodents amster) (Sauter and Glick, 1979). We could not detect galactosamine in SAF-protein samples suggesting that these proteins do not contain 0-linked sugars.…”

Suppression of lung metastasis of B16 mouse melanoma by N-acetylglucosaminyltransferase III gene transfection.

“…The glycopeptides in polyoma-transformed baby hamster kidney cells have unusually high molecular weights due to the presence of external sialic acid as well as galactose and GlcNAc (2). The predominant surface glycopeptide of baby hamster kidney cells transformed by Rous sarcoma virus was determined to be a triantennary, completely sialylated, complex glycopeptide containing a core region of Man, GlcNAc, and Fuc (3). Synthesis of these elongated branches is initiated by 6-N-acetylglucosaminyltransferase (GnT-V; EC 2.4.1.155), which catalyzes the formation of the (31-6 branch (4).…”