Prolactin receptor extracellular domain

Placental lactogen Prolactin receptor Extracellular domain Monomeric 1 2... 

Gerder, A., Grosclaude, J., Strasburger, C. J., Nir, S., and Djiane, J. (1996). Real-time kinetic measurements of the interactions between lactogenic hormones and prolactin-receptor extracellular domains from several species support the model of hormone-induced transient receptor dimerization. J. Biol. Ghent. 271(40), 24482-24491. 

The prolactin receptor, PER, which regulates milk production in mammals, belongs to the same receptor class as the growth hormone receptor. In addition to binding the hormone prolactin, PER also binds and is activated by growth hormone. The extracellular domain of PER forms a very stable 1 1 complex with growth hormone in solution this complex has been crystallized and its structure determined (Figure 13.21). We shall compare this structure with the 1 2 complex of the same hormone with GHR. 

Expression of the cDNA for the rabbit GH receptor and of the extracellular domain of the human receptor was obtained in transfected monkey COS-7 cells. The proteins so obtained bound 125I-labelled human GH, and showed a specificity similar to that of the receptors obtained from normal tissues. Thus, the rabbit receptor could bind human GH, bovine GH and to a lesser extent ovine prolactin, while the human receptor bound human GH but not bovine GH or ovine prolactin. This provides strong evidence that these receptors mediate the growth-promoting actions of GH, since biological responses show a similar specificity. 

In Plate 1, ref 2, 3, the crystal structures of hGH complexed with the extracellular domain of its receptor, referred to as hGH-binding protein, and of hGH complexed with the prolactin receptor are compared. Moreover, the effects of mutations of the hormone and the receptor on ligand binding are shown. 

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