Peptide hormones hormone-like

NET cells are characterized by their ability to take up and concentrate amine precursors such as dihydroxy-phenylalanine (DOPA) and hydroxytryptophane (HTP) and to produce amines and peptides, for which reason they were also classified as amine precursor uptake and decarboxylation (APUD) cells. They may also express different peptide hormone receptors (like somatostatin receptors) or transporters at their cell membrane. These uptake mechanisms and the presence of peptide receptors and transporters constitute the basis for the use of specific radiolabeled ligands for imaging of neuroendocrine tumors. 

Table 1. Structures of the Neurohypophyseal Hormone-Like Peptides, ...

Human tumor necrosis factor (TNF) (Fig. 1) is a hormone-like proinflammatory peptide belonging to the group of cytokines. It is mainly produced by cells of the immune system in response to infection, inflammation, or cell damage. Disregulated TNF is an important factor in many pathological situations, like sqDsis, rheumatoid arthritis, inflammatory bowel disease (Crohn s disease), and Cachexia. The cytotoxic activity of TNF is of interest in development of new antitumoral strategies. 

By far the most studied family of the G-protein-coupled receptors are the rhodopsin-like receptors. These are also the largest group of receptors in number as they include receptors not only for the monoamines, nucleotides, neuropeptides and peptide hormones, but they also include the odorant receptors which number several hundreds of related receptors. These receptors have short N-termini, a conserved disulphide bridge between the TM2-TM3 and TM4—TM5 extracellular domains, and variable-length C-termini. In some cases the C-terminus is myristolyated which by tying the C-terminus to the cell membrane generates a fourth intracellular loop. 

Membrane-associated receptors are linked to transducing proteins (like G-proteins) in the inner portion of the membrane. G-protein coupled receptor (GPCR) families comprise a major class of the receptors that are pharmacologically relevant, such as muscarinic acetyl choline receptors, adrenoceptors, dopamine receptors, serotonine, opiate, peptide hormone, purinerg receptors, and also sensory chemoreceptors. A large variety of subtypes are described in the pharmacological literature. 

Gordienko D V, Bolton TB, Cannell MB 1998 Variability in spontaneous subcellular Ca2+ release in guinea-pig ileum smooth muscle cells. J Physiol 507 707-720 Ho R, Shao Z 1991 Axial resolution of confocal microscopes revisited. Optiik 88 147—154 Holz GG, Leech CA, Heller RS, Castonguay N, Habener JF 1999 cAMP-dependent mobilization of intracellular Ca2+ stores by activation of ryanodine receptors in pancreatic [j cells. A Ca2+ signaling system stimulated by the insulinotropic hormone glucagon-like peptide-1-(7-37). J Biol Chem 274 14147-14156 Lipsius SL, Hiiser J, Blatter LA 2001 Intracellular Ca2+ release sparks atrial pacemaker activity. News Physiol Sci 16 101-106... 

As would be expected of active protein secreting cells, glandular epithelial tissue, the cytokine secreting cells of the immune system and the blood vessel endothelium, have an extensive internal structure consisting of rough endoplasmic reticulum and numerous mitochondria. Peptide hormones, growth factors and cytokines like all proteins are synthesized by DNA transcription and mRNA translation. The primary transcript of the mRNA may code for an inactive prohormone which requires careful proteolysis to produce the active hormone, as for example in the case of insulin. Adrenocorticotropic hormone (ACTH) is particularly interesting in this respect because... 

The animal organism contains more than 100 hormones and hormone-like substances, which can be classified either according to their structure or according to their function. In chemical terms, most hormones are amino add derivatives, peptides or proteins, or steroids. Hormones regulate the following processes ... 

Hydrophilic hormones and other water-soluble signaling substances have a variety of biosynthetic pathways. Amino acid derivatives arise in special metabolic pathways (see p. 352) or through post-translational modification (see p. 374). Proteohormones, like all proteins, result from translation in the ribosome (see p. 250). Small peptide hormones and neuropeptides, most of which only consist of 3-30 amino acids, are released from precursor proteins by proteolytic degradation. 

The incretin hormone glucagon-like peptide-1 (GLP-1) plays a crucial role in the regulation of insulin by acting on the pancreas to potentiate glucose-induced insulin secretion. GLP-1 is rapidly cleaved by serine protease dipeptidylpeptidase IV. The inhibitors of DDP-IV are new drugs for the oral treatment of type 2 diabetes. 

Until recently, stimulants and narcotics were the most sought drugs in athletics. To circumvent the rules, drugs that do not affect the mood find now large use, like substances that increase the red blood cells count (blood doping), diuretics, peptide hormones, beta-blocker, and anabolic steroids. 

AC2993/pept. structurally correlated to the human hormone glucagon-like peptide-1... 

Opium alkaloids are nonpeptide agonists for the opioid peptide hormone receptors. The dried latex of Papaver somniferum (opium), or the seed capsule of the plant itself, are the sources of almost 25 alkaloids. Some simple isoquinolines from opium, like papaverine (5.86), are antispasmodics. The principal alkaloid ( 10% of the total) is morphine (3.11), which is also an isoquinoline (rings C and E) but can addihonally be considered a phenanthrene derivahve (rings A, B, and C). 

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