Biosynthesis and molecular cloning of sulfated glycoprotein 2 secreted by rat Sertoli cells.
Sulfated glycoprotein 2 (SGP-2) is the major protein secreted by rat Sertoli cells. Pulse-chase labeling shows that SGP-2 is synthesized as a cotranslationally glycosylated 64-kDa precursor that is modified to a negatively charged 73-kDa form before intracellular cleavage to the mature 47- and 34-kDa subunits. A plasmid cDNA library was constructed from immunopurified mRNA, and a recombinant clone containing the entire protein coding sequence of SGP-2 was isolated. The 1857-nucleotide cDNA consists of a 297-nucleotide 5' noncoding segment, a 1341-nucleotide coding segment, and a 219-nucleotide 3' noncoding sequence. The 5' noncoding region contains five ATG codons followed by four short open reading frames. The derived SGP-2 sequence has a molecular weight of 51,379 and contains six potential N-glycosylation sites. Proteolytic processing sites for the preproprotein were determined by amino-terminal sequencing of the isolated SGP-2 subunits. Northern blots show a wide tissue distribution for the 2.0-kb SGP-2 message, and computer sequence analysis indicates a significant relationship between SGP-2 and human apolipoprotein A-I.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D051152:Clusterin; D004247:DNA / Q000378:metabolism; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D008297:Male; D018832:Molecular Chaperones; D010957:Plasmids; D011132:Polyribosomes; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D012708:Sertoli Cells / Q000378:metabolism*; D014158:Transcription, Genetic
C498500:Clu protein, rat; D051152:Clusterin; D006023:Glycoproteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D004247:DNA