title: Glycosylation reduces the bioactivity of calcitonin.
abstract: The biological significance of peptide hormone glycosylation is uncertain. To examine the effect of Asn-linked glycosylation on calcitonin's bioactivity we purified glycosylated calcitonin from a transplantable rat medullary thyroid carcinoma. Glycosylated calcitonin constituted 2.3% of the total extracted immunoreactive calcitonin. The structure of this peptide differed from nonglycosylated calcitonin only by the oligosaccharide modification of asparagine 3. Affinity of glycosylated calcitonin for lentil lectin indicated that the oligosaccharide was a complex processed form. In a standard in vivo bioassay glycosylated calcitonin had a markedly reduced hypocalcemic activity compared to nonglycosylated calcitonin, an effect most likely due to the presence of the oligosaccharide.
authors.affiliation: Medical Service, American Lake Veterans Administration Medical Center, Tacoma, WA 98493.
authors.forename: P J
authors.initials: PJ
authors.lastname: Gkonos
authors.forename: H
authors.initials: H
authors.lastname: Charbonneau
authors.forename: P T
authors.initials: PT
authors.lastname: Lawson
authors.forename: G A
authors.initials: GA
authors.lastname: Howard
authors.forename: R S
authors.initials: RS
authors.lastname: Birnbaum
authors.forename: B A
authors.initials: BA
authors.lastname: Roos
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001681:Biological Assay; D002116:Calcitonin / Q000302:isolation & purification / Q000494:pharmacology* / Q000502:physiology; D002118:Calcium / Q000097:blood*; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005688:Galactosamine / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D006031:Glycosylation; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D013964:Thyroid Neoplasms / Q000503:physiopathology
chemical_list: D000596:Amino Acids; D005688:Galactosamine; D002116:Calcitonin; D005944:Glucosamine; D002118:Calcium