| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
Human chorionic gonadotropin (hCG), luteinizing hormore (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) are a family of heterodimetric glycoprotein hormone that contain a common alpha-subunit, but differ in their hormone-specific beta-subunit. Processing of the N-limked oligosaccharide of the glycoprotein family is both tissue and dimer specific. LH,TSH,and free alpha synthesized in pituitary bear oligosaccharide terminating with sulfate (SO_4) and Nacetylgalactosamine (GalNAc), whereas the teimination of oligosaccharide in hCG synthesized in placenta and FSH is sialic acid and galactose. Using site-directed mutagenesis and gene tranfer, we studied the role of the Pro-Leu-Arg motif, which has been shown to be a recognition marker of glycoprotein hormone-specific GalNAc transferase, in sulfation on N-linked oligosaccharide in alpha-subunit. The wild-type or mutated alpha gene was transfected into GH_3 cells. Our data rebealed that substitution of the Pro-Leu-Arg motif by Ala-Leu-Ala did not affect the sulfation of N-linked oligosaccharide, but generated the attachement of O-linked oligosaccharide. alpha-Subunit containing either of the two N-linked glycosylations is also sulfated. We conclude that in GH_3 cells, the Pro-Leu-Arg motif plays no role in the sulfation of oligosaccharide in alpha-subunit, and both N-glycosylations are terminated with SO_4.
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