Glycoprotein variants

Finally, work that may facilitate understanding the role of oq-acid glycoprotein variants in inter-individual variations in plasma protein binding, pharmacokinetic behavior, and drug action has been described. A capillary zone electrophoresis method that allows for the determination of 11 intact forms (i.e., isoforms, glycoforms) of oq-acid glycoprotein has been described [84],... 

Miller J. L., Lyle V. A., Cunningham D. Mutation of leucine-57 to phenylalanine in a platelet glycoprotein Iba leucine tandem repeat occurring in patients with an autosomal dominant variant of Bemard-Soulier disease. Blood 1992 79,439-46. 

Davis, S.J., Ward, H.A., Puklavec, M.J. et al. (1990) High level expression in Chinese hamster ovary cells of soluble forms of CD4 T lymphocyte glycoprotein including glycosylation variants. The Journal of Biological Chemistry, 265 (18), 10410-10418. 

Bangs, J.D., Andrews, N.W., Hart, G.W., and Englund, P.T. (1986) Post-translational modification and intracellular transport of a trypanosome variant surface glycoprotein./. Cell Biol. 103, 255-263. 

K Schmid. Human plasma a,-acid glycoprotein—biochemical properties, the amino acid sequence and the structure of carbohydrate moiety, variants and polymorphism. In P Baumann, CB Eap, WE Muller, JP Tillement, eds. Al-pharacid glycoprotein genetics, biochemistry, physiological function, and pharmacology. Alan R. Liss, New York, 1989, pp 7-22. 

The closely related Trk B serves as a receptor for BDNF. Two variants of this glycoprotein have been characterized a larger (145 kDa) form and a truncated (95 kDa) form. While exhibiting identical extracellular domains, the 95 kDa protein has a short (23 amino acid) cytoplasmic region, whereas the 145 kDa form displays a larger (tyrosine kinase) cytoplasmic domain. Trk B also serves as a functional receptor for NT-3 and NT-4/5 and is expressed widely throughout the central and peripheral nervous system. 

Thyrotropin is a glycoprotein consisting of two peptide (alpha and beta) subunits joined noncovalently. The TSH-alpha subunit in humans has 89 amino acids and is virtually identical to that of the alpha subunit of FSH, LH, and hCG. The TSH-beta subunit has 112 amino acids and confers thyroid specificity. Carbohydrate side chains glycosylate each subunit prior to secretion and are important for hormone action. Native TSH is actually secreted as a mixture of glycosylation variants, having both sialylated and sulfated forms. 

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