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Glycosylated human growth hormone variant
J Ray1, B K Jones, S A Liebhaber
1Department of Human Genetics, University of Pennsylvania, Philadelphia 19103.
Endocrinology
|July 1, 1989
Summary
The human growth hormone variant (hGH-V) gene produces multiple protein isoforms. These placental growth hormone variants undergo N-linked glycosylation, a post-translational modification.
Area of Science:
- Endocrinology
- Molecular Biology
- Biochemistry
Background:
- The human growth hormone variant (hGH-V) gene is expressed in the placenta.
- Two mRNA forms, hGH-V and hGH-V2, are produced, encoding different protein sizes.
- hGH-V has a predicted N-linked glycosylation site absent in hGH-V2 and pituitary GH (hGH-N).
Purpose of the Study:
- To investigate post-translational modifications, specifically N-linked glycosylation, of hGH-V isoforms.
- To determine if secreted hGH-V proteins are glycosylated.
Main Methods:
- Transfected cell lines expressing hGH-N and hGH-V were utilized.
- Cells were treated with tunicamycin to inhibit glycosylation.
- Metabolically labeled proteins were digested with peptide:N-glycosidase F and endoglycosidase H.
Main Results:
- hGH-V transfection yielded 22, 24, and 26 kD proteins.
- Tunicamycin treatment and PNGase F digestion removed 24 and 26 kD bands, indicating N-linked glycosylation.
- Endoglycosidase H selectively removed the 24 kD band, suggesting specific glycosylation patterns.
Conclusions:
- The hGH-V gene products are subject to post-translational N-linked glycosylation.
- The 24 and 26 kD hGH-V isoforms are glycosylated in a fibroblastic cell line.
- These findings contribute to understanding placental growth hormone processing and function.