Different half-lives of the carbohydrate and protein moieties of a 110,000-dalton glycoprotein isolated from plasma membranes of rat liver.
By using a four-step procedure (i, solubilization with Triton X-100; ii, affinity chromatography on concanavalin A-Sepharose; iii, affinity chromatography on wheat germ lectin-Sepharose; iv, preparative sodium dodecyl sulfate gel electrophoresis) a glycoprotein was isolated from rat liver plasma membrane. The molecular weight is 110,000 and the isoelectric point is 5.8. It contains L-fucose, N-acetylneuraminic acid, D-galactose, D-mannose, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, and considerable quantities of aspartate, threonine, serine, and leucine. In pulse-chase experiments the half-lives of methionine and arginine, representing the half-life of the protein, were determined as 70 hr and 78 hr, respectively. The half-lives of the terminal carbohydrates L-fucose and N-acetylneuraminic acid were 12.5 and 33 hr, respectively. The galactose half-life was 20 hr. From this it is concluded that terminal sugars turn over several times in the life-span of this protein molecule. This process may be operative during membrane recycling mechanisms.
D000818:Animals; D001059:Apoproteins / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D007526:Isoelectric Point; D008099:Liver / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D051381:Rats; D013997:Time Factors
D001059:Apoproteins; D006023:Glycoproteins; D008565:Membrane Proteins