Sex hormone binding globulin
Sex hormone binding globulin | ||
---|---|---|
Model with 5α- dihydrotestosterone (green) according to PDB 1D2S | ||
Existing structural data: see UniProt |
||
Properties of human protein | ||
Mass / length primary structure | 373 amino acids | |
Secondary to quaternary structure | Homodimer | |
Isoforms | 2 | |
Identifier | ||
Gene name | SHBG | |
External IDs | ||
Occurrence | ||
Homology family | SHBG | |
Parent taxon | Euteleostomi |
Sex hormone binding globulin (SHBG) is a specific transport protein for sex hormones , especially testosterone and estradiol . These hormones bind in blood of vertebrates to SHBG, and to a lesser extent to albumin . Only a small percentage is unbound. Only this unbound part can become active in the target organs, SHBG has an inhibiting influence on their effect and is libido- lowering.
SHBG is produced by liver cells and released into the bloodstream. It is also produced by the brain , uterus , placenta, and vagina . SHBG produced by the testes is also known as androgen-binding protein . The sequence of the amino acids is the same, it only differs in a few functional sugar groups. The gene for SHBG is on chromosome 17 .
The concentration of SHBG in the blood is controlled by various stimulating and inhibiting factors. Insulin and insulin-like growth factor seem to have a lowering effect, as do high concentrations of androgen , while high estrogen and thyroxine concentrations increase the effect. More recent studies, however, suggest that gene expression is inhibited by the fat production of the liver cells, which results in a reduction in the concentration in the blood.
The SHBG concentration is chronically low in polycystic ovarian syndrome , diabetes mellitus and hypothyroidism . Increased concentrations can be found during pregnancy , with hyperthyroidism and anorexia nervosa .
In the laboratory, the simultaneous determination of SHBG and testosterone or estradiol can provide information about the concentration of the free, biologically active sex hormone.
swell
- ↑ Too much sugar turns off gene that controls the effects of sex steroids , accessed January 12, 2008
- ↑ a b Labor Lexicon for SHBG
Web links
- Sex hormone binding globulin. In: Online Mendelian Inheritance in Man . (English)