Biological Chemistry - Berezov T. T., Korovkin B. F. 1998

Hormones
Pituitary Hormones
Melanocyte-stimulating hormones (MSH, melanotropins)

Melanotropins are synthesized and secreted into the bloodstream by the intermediate lobe of the Pituitary Gland. The primary structures of Two Types of Hormones—alpha- and beta-melanocyte-stimulating hormones (α-MSH and β-MSH)—have been isolated and decoded. It has been found that in all examined animals, α-MSH consists of 13 amino acid residues arranged in an identical sequence:

Class="center">СН3-СО-Н-Сер-Тир-Сер-Мет-Глу-Гис-Фен-Арг-Трп-Гпи-Лиз-Про-Вал-СО-NH2,

In α-MSH, the N-terminal Serine is acetylated, and the C-terminal amino acid is represented by valine amide.

The Composition and Structure of β-MSH turned out to be more complex. In most animals, the β-MSH molecule consists of 18 amino acid residues; moreover, there are species-specific differences concerning The Nature of The amino acid at positions 2, 6, and 16 of the hormone's polypeptide chain. β-MSH isolated from the human intermediate pituitary lobe proved to be a 22-membered peptide, extended by 4 amino acid residues at the N-terminus:

Н-Ала-Глу-Лиз-Лиз-Дсп-Глу-Гли-Про-Тир-Арг-Мет-Глу-Гис-Фен- Арг-Трп-Гли-Сер-Про-Про-Лиз-Асп-ОН

The Physiological Role of melanotropins is to stimulate melanogenesis in mammals and increase the number of pigment Cells (melanocytes) in the Skin of amphibians. MSH may also influence fur coloration and the secretory function of Sebaceous Glands in animals.



Last update: 06/08/2026

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