INTERACTION BETWEEN THE HEPATIC GROWTH-HORMONE RECEPTOR AND CONCANAVALIN-A

The interaction between the plant lectin concanavalin A (Con A) and hepatic receptors for human growth hormone (GH) has been studied in paniculate and soluble microsomal membrane preparations from rabbit and rat liver. Con A shows a dose-dependent, partial (30%) inhibition of 125I-human GH binding which is reversed by the Con A competitor, α-methyl mannoside. The Con A effect is dependent on the receptor concentration. The inhibition by Con A in rabbit liver is a reflection of a decreased number of available binding sites - there is no effect on binding affinity. It would appear that Con A binds directly to the GH-binding protein and not to an adjacent membrane glycoprotein. The GH receptor may consist of more than one molecular species, differing only in the carbohydrate type or content. © 1979.