Biosynthesis of Collagen and Basement Membrane

Most of the hydroxylysine residues of basement membranes are linked to the disaccharide 2-O-a-D-glucosyl-D-galactose by -glycosidic bonds 

UDF-Gdactose Hydroxylysine-CoUagen (Basement Membrane) Galactosyltransferase 

The product of galactosyl transfer was characterized by the isolation, following alkaline hydrolysis, of a radioactive compound, which had the same migration characteristics upon Dowex 50 chromatography and paper electrophoresis as did galactosylhydroxylysine. After acid hydrolysis of the labeled compound, only galactose and hydroxylysine were detected, and all the radioactivity resided with galactose. 

Besides the acceptor collagen, several glycoproteins were tested for acceptor activity, including partially degraded preparations from which sialic acid and galactose had been removed. Only one such preparation, ob- 

The glycosylation of collagen and basement membrane has been the subject of a series of extensive investigations by M. J. Spiro and Spiro (1971) and R. G. Spiro and Spiro (1971a,b). The galactosyltransferase was purified from a high-speed supernatant (100,000 g) from kidney cortex of 10-day-old rats, and after ammonium sulfate fractionation and gel filtration on Bio-Gel A-1.5m a 12-fold purification had been achieved compared to the 10,000 g supernatant. 

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