Intracellular hormone receptors
Structure and nomenclature of corticosteroid products and selected synthetic derivatives. The structure of hydrocortisone is represented in two dimensions. It should be noted that the steroid ring system is not completely planar and that the orientation of the groups attached to the steroid rings is an important determinant of the biological activity. The methyl groups at C 18 and C19 and the hydroxyl group at C11 project upward (forward in the two-dimensional representation, shown by a solid line connecting the atoms) and are designated beta. The hydroxyl at C17 projects below the plane (behind in the two-dimensional representation, represented by dashed line connecting the atoms) and is designated alpha.