There is structural homology between relaxin, insulin, and the somatomedins. Structure and potency of relaxin is poorly conserved across species. Relaxin causes dilation of the cervix, relaxation of pelvic ligaments, and coordinates uterine contractions during the birth process. A prepro leader sequence and bioactive C-terminal fragments are cleaved from the mature MIH protein. Steroid hormones are derived from cholesterol.
Endocytotic vesicles lose their coating and coalesce to form an endosome.
The placenta is a major source of steroid hormones during pregnancy. However, there is some evidence that steroids are packaged into secretory granules and released from the cell by exocytosis. Steroid hormones are only sparingly soluble within plasma. Steroid hormones are metabolized primarily within the liver. The steroid molecule is inactivated by saturation.