Pancreatic polypeptides

Pancreatic polypeptide, a peptide of 36 amino acids, is secreted in response to fuel ingestion and potentially affects pancreatic exocrine secretion of bicarbonate and protein. 

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Example Crippen and Snow reported their success in developing a simplified potential for protein folding. In their model, single points represent amino acids. For the avian pancreatic polypeptide, the native structure is not at a potential minimum. However, a global search found that the most stable potential minimum had only a 1.8 Angstrom root-mean-square deviation from the native structure. 

Neuropeptide Y. Neuropeptide Y [82785 5-3] (NPY) (255) is a 36-amiao acid peptide that is a member of a peptide family including peptide YY (PYY) [81858-94-8, 106338-42-5] (256) and pancreatic polypeptide (PPY) [59763-91-6] (257). In the periphery, NPY is present in most sympathetic nerve fibers, particulady around blood vessels and also in noradrenergic perivascular and selected parasympathetic nerves (66). Neurons containing NPY-like immunoreactivity ate abundant in the central nervous system, particulady in limbic stmctures. Coexistence with somatostatin and NADPH-diaphorase, an enzyme associated with NO synthesis, is common in the cortex and striatum. 

Neuropeptide Y (NPY) is a 36 amino acid polypqrtide with tyrosine residues at both ends of the molecule. It is characterised structurally by a PP-fold consisting of an extended polyproline helix and an a-helix connected by a (3-tum [1]. Based on structural and evolutionary criteria, NPY is closely related to peptide YY (PYY) and pancreatic polypeptide (PP). 

Michel MC, Beck-Sickinger AG, H Cox et al (1998) XVI. International Union of Pharmacology recommendations for the nomenclature of neuropeptide Y, peptide YY and pancreatic polypeptide receptors. Pharmacol Rev 50 143-150... 

The hormone pancreatic polypeptide (PP) is a 36 amino acid peptide, which is closely related to neuropeptide Y and peptide YY PP is mainly found in pancreatic cells distinct from those storing insulin, glucagon or somatostatin. It acts on receptors that belong to the family of neuropeptide Y receptors, particularly on the Y4 subtype. 

Pancreatic Polypeptide Nuclear Receptor Regulation of Hepatic Cytochrome P450 Enzymes... 

The neuropeptide Y (NPY) belongs to a family of peptides that includes peptide YY and pancreatic polypeptide, and it is associated with several diseases such as asthma, immune system disorders, inflammatory diseases, anxiety, depression and diabetes mellitus. NPY is found in the central and peripheral nervous system, and its biological functions are mediated by interactions with five receptor sub-types, i.e. Yl, Y2, Y4, Y5 and Y6. Several studies indicate that the feeding behavior is influenced by interactions between NPY and Yl and Y5. Deswal and Roy used Cerius descriptors and genetic function approximation QSAR to investigate the structural determinants for the inhibition potency of 24 compounds with the general structure 4 for the NPY Y5 receptor [31]. The best QSAR (H = 0.720,... 

The endogenous release of the potent vasoconstrictor neuropeptide Y (NPY) is increased during sepsis and the highest levels are detected in patients with shock (A8). NPY is a 36-amino-acid peptide belonging to the pancreatic polypeptide family of neuroendocrine peptides (T2). It is one of the most abundant peptides present in the brain and is widely expressed by neurons in the central and peripheral nervous systems as well as the adrenal medulla (A3). NPY coexists with norepinephrine in peripheral sympathetic nerves and is released together with norepinephrine (LI9, W14). NPY causes direct vasoconstriction of cerebral, coronary, and mesenteric arteries and also potentiates norepinephrine-induced vasoconstriction in these arterial beds (T8). It appears that vasoconstriction caused by NPY does not counterbalance the vasodilatator effects of substance P in patients with sepsis. The properties of vasodilatation and smooth muscle contraction of substance P are well known (14), but because of the morphological distribution and the neuroendocrine effects a possible stress hormone function for substance P was also advocated (J7). Substance P, which is a potent vasodilatator agent and has an innervation pathway similar to that of NPY, shows a low plasma concentration in septic patients with and without shock (A8). 

Smart, D.S., Shaw, C., Johnston, C.F., Halton, D.W., Fairweather, I. and Buchanan, K.D. (1992a) Chromatographic and immunological characterisation of immunoreactivity towards pancreatic polypeptide and neuropeptide Y in the nematode Ascaris suum. Comparative Biochemistry and Physiology 102C, 477—481. 

Specific hormones Insulin, glucagon, somatostatin, gastrin, pancreatic polypeptide, serotonin, vasoactive intestinal peptide, cholecystokinin... 

Additional impurities, such as glucagon, somatostatin, pancreatic polypeptide and vasoactive intestinal polypeptide, are present in most conventional insulin preparations at lower levels. The presence of such contaminants can impact upon product safety and efficacy in a number of ways. 

Neuropeptide Y (NPY) is a highly conserved 36 amino acid peptide of the pancreatic polypeptide family that is widely distributed throughout the mammalian brain. Y1 and Y2 receptors represent the major subtypes expressed in brain areas known to be activated upon anxiogenic stimulation, thus providing the rationale for studying the involvement of NPY and its receptor subtypes in anxiety-related behaviour (Kask et al. 2002). Other receptor subtypes in... 

D. Larhammar (1996). Structural diversity of receptors for neuropeptide Y, peptide YY and pancreatic polypeptide. Regul. Pept. 65 165. 

Neuropeptide Y (NPY) is a member of the family that also includes peptide YY and pancreatic polypeptide. Each peptide consists of 36 amino acids. 

NPY is one of the most abundant neuropeptides in both the central and peripheral nervous systems. In the sympathetic nervous system, NPY is frequently localized in noradrenergic neurons and apparently functions both as a vasoconstrictor and as a cotransmitter with norepinephrine. Peptide YY and pancreatic polypeptide are both gut endocrine peptides. 

These diverse effects are mediated by multiple receptors designated Y through Y 6. All receptors except Y3 have been cloned and shown to be G protein-coupled receptors linked to mobilization of Ca2+ and inhibition of adenylyl cyclase. Yj and Y2 receptors are of major importance in the cardiovascular and other peripheral effects of the peptide. Y4 receptors have a high affinity for pancreatic polypeptide and may be a receptor for the pancreatic peptide rather than for NPY. Y5 receptors are found mainly in the central nervous system and... 

With in pancreatic polypeptide-rich lobules of adult islets, located only in the posterior portion of the head of the human pancreas, glucagon cells are scarce (< 0.5%) and F cells make up as much as 80% of the cells. 

It inhibits the secretion of numerous hormones and transmitters, including gastrin, cholecystokinin, glucagon, growth hormone, insulin, secretin, pancreatic polypeptide, vasoactive intestinal peptide, and 5-HT. 

Figure 30-5 Structure of the avian pancreatic polypeptide, a small globular protein. From Blundell et al.107...

The 36-residue pancreatic polypeptide is a hormone of uncertain functions. The crystalline polypeptide has at the N terminus an 8-residue collagenlike helix that lies parallel to a C-terminal a helix (Fig. 30-5). The overall shape resembles that of both insulin and glucagon.107 108 This PP-fold includes also neuropeptide Y, which is considered in the next section,109 and neuropeptide YY.110... 

Neuropeptides Y (NFY) and YY are 36-residue amidated peptides that are members of the pancreatic polypeptide (PP) family (Fig. 30-5). NPY is produced both in the peripheral nervous system and in the brain,110 134 where it is one of the most abundant neuropeptides. Another member of the PP family is semi-nalplasmin, a regulator of calcium ion transport in bovine sperm.135 NPY is best known for its stimulation of appetite. It also inhibits anxiety and increases memory retention. It has a vasoconstrictive effect on blood vessels, participating in cardiovascular regulation.136 137 Peptide YY is formed in endocrine cells of the intestine, while NPY is formed in neurons of the parasympathetic system.138 Both participate in regulation of fluid and electrolyte secretion. Both are found in other vertebrate species.139... 

Pancreatic polypeptide Polypeptide (36 residues) Glycogenolysis, gastrointestinal regulation... 

The pancreatic islets consist of four primary cell types alpha (A) cells, which produce glucagon beta (B) cells, which produce insulin delta (D) cells, which produce somatostatin and (F) cells, which produce pancreatic polypeptide. As previously mentioned, this chapter focuses on the functions of insulin and glucagon. The exact physiologic roles of the other pancreatic hormones are not entirely clear. For example, the function of the pancreatic polypeptide released from pancreatic F cells remains to be determined. 

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