Binding activities of hepatic extracts of the rat, chicken, frog and fish for 125I-labeled asialo-, agalacto-, and aN-acetylglucosamino-derivatives of orosomucoid and haptoglobin, were determined. 2. Hepatic receptors of the rat were found to bind preferably asialo-derivatives, those of the chicken agalacto-ones. 3. Hepatic receptors of lower vertebrates showed much lower affinity, in the case of the frog for all the modified glycoproteins whereas in the case of the fish with the exception of aN-acetylglucosamino-derivatives which were not bound at all. 4. Specific binding of derivatives of orosomucoid was higher than that of haptoglobin but equal in terms of molarity.
