the neuron thereby enabling visual perception. Activators of nuclear receptors See the main article on nuclear receptors Steroid Hormones This large and diverse class of steroids are biosynthesized from isoprenoids and structurally resemble cholesterol. Mammalian steroid hormones can be grouped into five groups by the receptors to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestogens. Retinoic acid Retinol (vitamin A) can be metabolized to retinoic acid which activates nuclear receptors such as the RAR to control differentiation and proliferation of many types of cells during development. Prostaglandins The majority of prostaglandin signaling occurs via GPCRs (see above) although certain prostaglandins activate nuclear receptors in the PPAR family. (See article eicosanoid receptors for more information). See also Allostery Cell signaling Protein dynamics Lysophospholipid receptors List of signaling molecule types References Signal transduction