title: Sulfation of the choriogonadotropin alpha subunit in human placental explants.
abstract: Incubation of first trimester placental explants with [35S]O4 resulted in incorporation of radioactive sulfate into free and dimer forms of alpha subunit of human chorionic gonadotropin. Sulfate was not attached to N-linked oligosaccharides since it was not released by endoglycosidase F. Analysis of pronase digest revealed the presence of tyrosine-O-[35S]O4. Comparison of tryptic peptides of alpha subunit labeled with several amino acids identified the penultimate carboxyterminal peptide as the sulfation site. Since the C-terminal region of the hCG alpha plays a critical role in receptor binding of the hormone, modification in this region may regulate hormonal activity.
mesh_terms: D006063:Chorionic Gonadotropin / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006026:Glycoside Hydrolases; D006801:Humans; D046911:Macromolecular Substances; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D010446:Peptide Fragments / Q000032:analysis; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D013431:Sulfates / Q000378:metabolism*
chemical_list: D006063:Chorionic Gonadotropin; D046911:Macromolecular Substances; D010446:Peptide Fragments; D013431:Sulfates; D006026:Glycoside Hydrolases; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase