Studies with anti-growth hormone receptor antibodies

Antisera against a partially purified growth hormone receptor derived from rabbit liver were generated in guinea pigs. The antisera specifically inhibited the binding of 125I-ovine growth hormone (oGH) to liver membranes but had no effect on the binding of 125I-ovine prolactin to rabbit mammary gland receptors. These antisera did not bind or destroy 125I-oGH. Moreover, the binding of labeled growth hormone to membrane particles derived from liver of several species was also inhibited by the antisera, thus suggesting that immunological determinants of the growth hormone receptor of several species are similar. gamma-Globulin fractions derived from the antisera were responsible for the inhibition. In addition 125I-gamma-globulin derived from one antiserum bound to membrane pellets with a corresponding decline in 125I-oGH binding. Kinetic analysis of inhibition of 125I-oGH binding suggested a hyperbolic competitive inhibition, a point of view which is favored by the demonstration of a hormone receptor . antibody complex. The availability of the antireceptor sera confirmed previous data that differential affinity chromatography separated growth hormone and prolactin receptors in solubilized rabbit liver membrane preparations. The antireceptor sera will be useful probes in further characterization of the growth hormone receptor.