Growth hormone-binding sites in chicken hypothalamus

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Abstract
Specific binding of 125I-labelled recombinant DNA-derived chicken GH (rcGH; 2·1±0·41 (s.e.m.) % of total counts) and of 125I-labelled bovine GH (1·80±0·27% of total counts) to crude plasma membranes of the chicken hypothalamus was demonstrated. Binding of 125I-labelled rcGH was related to the amount of tissue incubated and was significant over the range 250–950 μg membrane protein per tube. Binding of 125I-labelled rcGH was saturable over the range 0·14–0·40 pmol and was to a single class of high-affinity (33·5 pm) low-capacity (2·14 fmol/mg protein) binding site. Binding of 125I-labelled rcGH was displaced by ovine GH and by ovine prolactin. These results demonstrate, for the first time, central GH-binding sites in a vertebrate species.