Purification and characterization of a sulfated glycoprotein secreted by Sertoli cells.
Sulfated glycoprotein 2 (SGP-2), the major secretion product of Sertoli cells, was purified from cell culture medium by reverse-phase high-performance liquid chromatography. The native protein consists of disulfide-linked monomers of 41,000 and 29,000 daltons which have a strong tendency to associate into multimers. The purified SGP-2 was subjected to amino acid analysis and contained high levels of Asx (11.1%), Glx (15.1%), and leucine (11.5%). The oligosaccharides on the purified SGP-2 were analyzed to determine the monosaccharide compositions and the molecular weights of the intact carbohydrate moieties. SGP-2 was shown to be 23.7% carbohydrate and consisted of 1% fucose, 3.5% mannose, 4.1% galactose, 7.1% N-acetylglucosamine, and 8.0% N-acetylneuraminic acid. No N-acetylgalactosamine was detected. When the SGP-2 was digested with proteases, the intact oligosaccharides were chromatographed over a Bio-Gel P-6 column and found to elute in a single symmetrical peak of approximately 3,300 g/mol. On the basis of these results, the oligosaccharides on SGP-2 were proposed to consist of triantennary chains similar to those found on fetuin. When the 35SO4(2-)-labeled SGP-2 was digested with Pronase, the free amino acids could be separated by chromatography from the oligosaccharide. The 35SO4(2-) was shown to be associated with the oligosaccharide portion of SGP-2.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002478:Cells, Cultured; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D051152:Clusterin; D006023:Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D018832:Molecular Chaperones; D008970:Molecular Weight; D051381:Rats; D012708:Sertoli Cells / Q000378:metabolism*
D000596:Amino Acids; D002241:Carbohydrates; D051152:Clusterin; D006023:Glycoproteins; D018832:Molecular Chaperones