Growth-hormone binding-sites are present in tissues of the porcupine Hystrix-hodgesoni, the snakehead Channa-maculata and the Winter flounder Pleuronectres-americanus but not in those of the lamprey Petromyzon-marinus

1. Various tissues of the porcupine Hystrix hodgesoni including liver, intestine, stomach, spleen, kidney, brain and lung were examined for the presence of growth hormone binding sites. 2. Membranes were prepared from the aforementioned tissues and tested for binding to I-125-bovine growth hormone (I-125-bGH). 3. Porcupine kidney membranes yielded 1.3 and 2.7% specific binding when tested at 1000 and 2500 mug protein, respectively. Porcupine liver membranes demonstrated approximately 1% specific binding at 3000,ug protein. The other tissues gave low specific binding. The results indicate that porcupine kidney contained binding sites for growth hormone. 4. Various tissues of two teleosts, the snakehead Channa maculata and the winter founder Pleuronectes americanus, were similarly processed and tested for binding to I-125-bGH. It was found that among the different tissues studied, the liver membranes of Channa maculata and the gonad membranes of Pleuronectes americanus gave the highest specific binding of I-125-bGH. 5. Liver and intestine membranes of the lamprey Petromyzon marinus did not bind I-125-bGH.