Recombinant Mouse Prolactin Protein

Prolactin (gene name PRL) is a secreted neuroendocrine pituitary hormone that acts primarily on the mammary gland to promote lactation, but has pleiotropic effects in both males and females (1-3). Mouse Prolactin is predominantly found as 23 kDa non-glycosylated monomers. Mouse prolactin shares 60% and 85% amino acid sequence identity with human and rat prolactin, respectively; however, activation of the human prolactin receptor by rat prolactin has been demonstrated (3). Prolactin is synthesized mainly by the anterior pituitary in all mammals, where secretion is under tonic inhibition by hypothalamic dopamine (2, 3). Secretion can be stimulated by suckling and diurnally by estradiol in rodents during pro-estrus and mating (2). In humans prolactin is also produced peripherally, while in rodents, the only known non-pituitary source is the placenta (1-3). Mouse serum Prolactin declines until mid-pregnancy, but increases in late pregnancy (1). Post-translational modifications such as polymerization, phosphorylation, and proteolytic cleavage can alter the activities of prolactin (3). Cleavage by matrix metalloproteinases or Cathepsin D can produce N-terminal 16 kDa antiangiogenic fragments also called vasoinhibins (4, 5). Thrombin can produce C-terminal 16 kDa fragments that are not antiangiogenic (3). The prolactin receptor (gene name PRLR) is a transmembrane type I glycoprotein that belongs to the cytokine hematopoietic receptor family. Expression of the prolactin receptor is widespread (2, 3). Each prolactin molecule is thought to bind two receptor molecules (6).