Prolactin is a single-chain protein hormone closely related to growth hormone. It is secreted by so-called lactotrophs in the anterior pituitary. It is also synthesized and secreted by a broad range of other cells in the body, most prominently various immune cells, the brain and the decidua of the pregnant uterus.
Prolactin is synthesized as a prohormone. Following cleavage of the signal peptide, the length of the mature hormone is between 194 and 199 amino acids, depending on species. Hormone structure is stabilized by three intramolecular disulfide bonds.
The conventional view of prolactin is that its major target organ is the mammary gland, and stimulating mammary gland development and milk production pretty well define its functions. Such a picture is true as far as goes, but it fails to convey an accurate depiction of this multifunctional hormone.
It is difficult to point to a tissue that does not express prolactin receptors, and although the anterior pituitary is the major source of prolactin, the hormone is synthesized and secreted in many other tissues. Overall, several hundred different actions have been reported for prolactin in various species.
Prolactin is synthesized as a prohormone. Following cleavage of the signal peptide, the length of the mature hormone is between 194 and 199 amino acids, depending on species. Hormone structure is stabilized by three intramolecular disulfide bonds.
The conventional view of prolactin is that its major target organ is the mammary gland, and stimulating mammary gland development and milk production pretty well define its functions. Such a picture is true as far as goes, but it fails to convey an accurate depiction of this multifunctional hormone.
It is difficult to point to a tissue that does not express prolactin receptors, and although the anterior pituitary is the major source of prolactin, the hormone is synthesized and secreted in many other tissues. Overall, several hundred different actions have been reported for prolactin in various species.
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