Prorelaxin H2, also known as RLN2, belongs to the insulin gene superfamily. This family is produced by the ovary, and targets the mammalian reproductive system to ripen the cervix, elongate the pubic symphysis and inhibit uterine contraction. It may have additional roles in enhancing sperm motility, regulating blood pressure, controlling heart rate and releasing oxytocin and vasopressin. RLN2 is a peptide hormone associated with a number of therapeutically relevant physiological effects, including regulation of collagen metabolism and multiple vascular control pathways. RLN1 and RLN2 share high sequence homology. Recombinant human RLN2 protein, fused to His-tag at N-terminus, was expressed in E.coli.