Cross-linking of iodinated prolactin to rat liver nuclear protein.

The specific binding of prolactin (PRL) in rat liver nuclei have been examined. Following cross-linking with the use of 125I-rat prolactin and autoradiography the evidence is presented for the specific binding of PRL to a nuclear protein with low Mr of about 7000. This study shows that the PRL binder in rat liver nuclei is a small protein and probably differs from molecular form of the rat liver membrane prolactin receptor.