Glycoprotein: glycosyl transferase activities of rat kidney were studied after subcutaneous injection of cortisone acetate or folic acid, or both. Whereas cortisone acetate had little effect, large increases in glycoprotein: glycosyl transferase activities were found 42 h after administration of folic acid. At this time, sialic acid transferase levels were about twice control values; collagen: glucosyl and collagen: galactosyl transferase activities were increased about threefold and twofold, respectively ; and fetuin: galactosyl transferase activity was almost fourfold higher than control. Some transferase activities were elevated by 17 h after injection of folate and remained above control values 140 h after injection. Cortisone injection had little effect on the folate-induced enzyme changes. These studies are compared with previous results concerning renal hypertrophy after injected folic acid. Although the results are compatible with a nonspecific increased rate of glycoprotein synthesis required for a newly proliferating cell population, the possibility of a more selective action of folic acid on glycoprotein: glycosyl enzyme activities is considered.
Rat kidney plasma membrane preparations and suspensions of intact glomeruli were used to study glycoprotein: glycosyl transferase activities present on cell surfaces. Collagen: glucosyl, fetuin: galactosyl, and fetuin: sialic acid (sialíc acid is the generic term for N-acetylneuraminic acid, NANA) transferase activities were increased from 1.9- to 5.6-fold in membrane preparations compared to whole tissue homogenates. Considerable activity was found with suspensions of glomeruli though in each assay specific activity was substantially less than for glomeruli homogenized and sonicated in buffer containing the nonionic detergent Triton X-100. For both membranes and glomeruli, collagen: glucosyl and fetuin: galactosyl transferase activities were enhanced by addition of folic acid whereas sialic acid transferase activity was reduced.
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