Isolation and Partial Characterization of Secreted Hamster Pituitary Prolactin

PRL secreted by hamster anterior pituitaries was purified by gel filtration on Sephadex G-100 and ion exchange chromatography on DEAE-cellulose. Hamster PRL eluted from Sephadex G-100 with an elution volume to void volume ratio of 1.85 and at a salt concentration of 0.13 M NaCl on DEAE-cellulose. Electrophoretic homogeneity of the hormone was demonstrated in several gel systems, and electrophoresis in the presence of sodium dodecyl sulfate indicated a molecular weight of 22,000 +/- 2,000. Hamster PRL did not cross-react with antiserum to mouse PRL. Hamster PRL displayed lactogenic activity in an in vitro mouse mammary gland assay. Hamster PRL displaced [125I]iodo-PRL from lactating rabbit mammary gland receptors. Thus, with respect to its exclusion properties on SEphadex G-100, its molecular weight, and its biological activity, hamster PRL closely resembles other mammalian PRLs.