Blockade of prolactin action by an antiserum to its receptors.

A guinea pig antiserum to prolactin receptors selectively inhibited the binding of [125I] prolactin to its membrane receptors as well as prolactin-mediated incorporation of [3H] leucine into casein and transport of [14C] aminoisobutyric acid, but was without effect on the binding of [125I] insulin and insulin-mediated events in explants of rabbit mammary glands maintained in culture. These findings provide direct evidence for an obligatory functional role of a membrane receptor in mediating the action of a polypeptide hormone.