Prorelaxin H1, which is encoded by RLN1 gene, is a 185 aa. protein. it is a heterodimer of a B chain and an A chain linked by two disulfide bonds. This protein belongs to the insulin family, and usually expressed in prostate but not in placenta, decidua or ovary. Relaxin is an ovarian hormone that acts with estrogen to produce dilatation of the birth canal in many mammals. It may be involved in remodeling of connective tissues during pregnancy, promoting growth of pubic ligaments and ripening of the cervix.