Sex-hormone binding globulin from sheep serum: purification and effects of pregnancy and treatment with exogenous estradiol.
Sex-hormone binding globulin (SHBG) is a protein that binds sex steroids in the serum of many species. SHBG binds androgens and estrogens in humans and primates with high affinity, but behaves as an androgen binding protein in other species. Here we purified SHBG from ewe and ram sera to homogeneity, by a simple and rapid method. The K(D) of the purified protein was found to be 3.63 nM for testosterone and around 600 nM for estradiol. We also studied the effect of pregnancy on SHBG levels in ewes and the effect of exogenous estradiol administration either orally or parenterally on SHBG levels in rams. Basal levels of SHBG in sheep are not affected by pregnancy or exposure to exogenous estradiol. It is concluded that SHBG regulation of expression in ewes and rams differs from that in humans in that it is not affected by estrogen and possibly is species specific.
Kouretas
D
D
Laboratory of Animal Physiology, School of Agriculture, University of Thessaly, Volos, Greece. dkouret@agr.uth.gr
Laliotis
V
V
Taitzoglou
I
I
Georgellis
A
A
Tsantarliotou
M
M
Mougios
V
V
Amiridis
G
G
Antonoglou
O
O
D000284:Administration, Oral; D000818:Animals; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007273:Injections, Intramuscular; D008297:Male; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*; D011485:Protein Binding; D012738:Sex Hormone-Binding Globulin / Q000302:isolation & purification* / Q000378:metabolism; D012756:Sheep / Q000097:blood*; D013739:Testosterone / Q000378:metabolism
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol