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" The information in this table was abstracted from Wilding, J. P. H., Ghatei, M. A., and Bloom, S. R. (1995). Hormones of the Gastrointestinal tract. In "Endocrinology" (L. J. DeGroot, M. Besser, H. G. Burger, J. L. Jameson, D. L. Loriaux, J. C. Marshall, W. D. Odell, J. T. Potts, Jr., and A. H„ Rubenstein, eds.), Vol. 3, Chapter 153, pp. 2870-2894. W. B. Saunders, Philadelphia, PA.

" The information in this table was abstracted from Wilding, J. P. H., Ghatei, M. A., and Bloom, S. R. (1995). Hormones of the Gastrointestinal tract. In "Endocrinology" (L. J. DeGroot, M. Besser, H. G. Burger, J. L. Jameson, D. L. Loriaux, J. C. Marshall, W. D. Odell, J. T. Potts, Jr., and A. H„ Rubenstein, eds.), Vol. 3, Chapter 153, pp. 2870-2894. W. B. Saunders, Philadelphia, PA.

first isolated from the hypothalamus, where it functions to inhibit the secretion of growth hormone (see Figure 3-8).

While the principal form of somatostatin is the SS-14 species, both SS-14 and SS-28 display overlapping but distinct biological activities and act through different receptors (see Table 8-7). It is known, however, that the 14 amino acids at the N-terminus of SS-28 have no intrinsic biological activity. Aspects of the actions of somatostatin are also covered in Chapters 3 and 7.

L. Bombesin and Tachykinin Peptide Families

The bombesins include structurally related peptides that were first isolated from amphibian skin and that were found to be biologically active in the GI tract. Later, additional members of the bombesin family were isolated directly from the gut, e.g., gastrin-releasing peptide (GRP) and neuromedin B; they are tabulated in Table 8-8 and their amino acid sequences are presented in Figure 8-11. In amphibians, three subfamilies of the bombesin family have been identified; these include the bombesins, the ranatensins, and the phylloitorins. Each subfamily is characterized by a common amino acid near its carboxy-terminus.

The tachykinins comprise three related mammalian-derived peptides, substance P, neurokinin A, and neurokinin B; each of these hormones also displays some structural homology to portions of the bombesins (see also Table 8-8 and Figure 8-11). Substance P, which was discovered in 1931, was the first peptide to be found in both the brain and the GI tract.

The tachykinins (fast acting), which mediate rapid contractions of smooth muscle, are so named to distin guish them from bradykinins (see Chapter 15), which have a much slower action on smooth muscle. The tachykinin-related peptides are characterized by a COOH-terminal sequence—Phe-X-Gly-Leu-Met-NH2 (see Figure 8-11).

The pattern of biological responses generated by the tachykinins is complex and includes smooth muscle contraction, hyperalgesia, activation of most cells (see Chapter 15), release of histamine from salivary cells, and involvement with asthma, hay fever, migraine headache, and inflammatory bowel disease. Three distinct tachykinin receptors have been cloned and found to belong to the seven transmembrane proteins that are coupled to G proteins (see Figure 1-23).

M. Calcitonin Gene-Related Peptide

Calcitonin gene-regulated peptide (CGRP) was the first neuropeptide to be discovered solely by molecular biology techniques. CGRP represents an alternative splicing of the mRNA transcribed from the calcitonin gene (see Figure 9-4); the mature hormone has 37 amino acids.

CGRP is widely distributed throughout the CNS and selected regions of the GI tract, particularly in sensory neurons. The Gl-related biological effects of CGRP include stimulation of somatostatin secretion, smooth muscle contraction, and increases in mucosal blood flow.

N. Endothelin

Endothelin is a 21-amino-acid peptide that is a highly potent vasoconstrictor. The endothelins are discussed in detail in Chapter 15 (see Figures 15-13,15-

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Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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