The protenin is a receptor for the anterior pituitary hormone, prolactin, and belongs to the type I cytokine receptor family. Prolactin-dependent signaling occurs as the result of ligand-induced dimerization of the prolactin receptor. Several alternatively spliced transcript variants encoding different membrane-bound and soluble isoforms have been described for this gene, which may function to modulate the endocrine and autocrine effects of prolactin in normal tissue and cancer.