Group-specific component (Gc) proteins bind vitamin D and 25-hydroxyvitamin D.

Group-specific component (Gc) proteins are human plasma proteins for which a worldwide polymorphism exists. As yet no functional role has been assigned this protein. We show that the products of both Gc alleles, proteins Gc 1 and Gc 2 (distinguished electrophoretically), bind substantial quantities of vitamin D and 25-hydroxyvitamin D.

Ethnic variation in genetic disease: possible roles of hitchhiking and epistasis.

The high incidence of some genetic diseases in certain ethnic groups is important in planning of medical genetic programs. Simple interaction models predict that at least some lethal recessive alleles will have "hitchhiked" to increased frequencies because of linkage to genes whose alleles have been favored by selection for other reasons in certain populations. In the absence of linkage or epistasis with a gene favored by selection, heterozygote advantage for a recessive lethal may produce the same phenomenon.

Serotonin binding proteins from human blood platelets. An experimental model system for studies on properties of synaptic vesicles.

Serotonin uptake, binding and release were studied in human blood platelets. The uptake showed marked individual differences while the loss of 5-HT during resuspension of the 5-HT loaded platelets was constant. The existence of 5-HT binding proteins was demonstrated by equilibrium dialysis, gel filtration on a column equilibrated with 5-HT, affinity chromatography on a 5-HT-Sepharose column and polyacryl-amide disc gel electrophoresis experiments.

Metabolic studies in the African pygmy.

Major metabolic effects of human growth hormone (HGH) were assessed in the African Babinga pygmy. Plasma free fatty acid (FFA) and glucose concentrations were measured in pygmies, HGH-deficient dwarfs, Bantu tribesmen, and Caucasian controls after each received 4 mg of HGH intravenously over a 20 min period. Pygmies had an early decrease of plasma FFA and glucose concentration, but did not exhibit a later lipolytic response.