Affordable Access

Genetic polymorphism of the human sex hormone-binding globulin: evidence of an isoelectric focusing variant with normal androgen-binding affinities.

Authors
  • Larrea, F1
  • Oliart, R M
  • Granados, J
  • Mutchinick, O
  • Diaz-Sanchez, V
  • Musto, N A
  • 1 Department of Reproductive Biology, Instituto Nacional de la Nutricion Salvador Zubiran, Mexico. , (Iran)
Type
Published Article
Journal
Journal of steroid biochemistry
Publication Date
Aug 28, 1990
Volume
36
Issue
6
Pages
541–548
Identifiers
PMID: 2214771
Source
Medline
Language
English
License
Unknown

Abstract

Human sex hormone-binding globulin (hSHBG) is a plasma glycoprotein composed of two identical subunits. The protein, which has high affinity for testosterone and estradiol has been purified to homogeneity. In this study we have investigated, on neuraminidase-treated serum samples, the presence of genetic variations of hSHBG by polyacrylamide gel isoelectric focusing (IEF). Based on IEF analyses of 110 serum samples from adult Mexican individuals we have identified two distinct IEF-patterns. The most frequent phenotype (95.45%) was characterized by two IEF-bands with pIs of 6.50 and 6.63, respectively. In five serum samples, a different 4-band pattern with pIs of 6.50, 6.63, 6.70 and 6.76 was identified. Family studies showed that this pattern was genetically determined. The frequency of this variant was 4.55%, and the observed phenotypes were consistent with the expression of an autosomal genetic system. The estimated gene frequencies for both alleles were shown to be in genetic equilibrium. Affinity constants, binding kinetics and serum concentrations of hSHBG from individuals having a 4-band pattern were similar to those obtained in individuals with a 2-band pattern, thus suggesting that the mechanism responsible for the generation of polymorphic variants of hSHBG reported herein did not involve the steroid binding site of the molecule. These findings may be of broad interest, as other serum binding proteins express genetic variants, which may permit their further structural and functional subclassification.

Report this publication

Statistics

Seen <100 times