Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been demonstrated [Shields, D. (1980) J. Biol. Chem. 255, 11625-11628] that mRNA isolated from the islets of Langerhans codes for two preposomatostatin molecules of apparent molecular weights 18,000 and 19,000, respectively. Here evidence is presented that in vitro translation of pancreatic islet mRNA in two different cell-free protein-synthesizing systems directs the synthesis of up to nine distinct forms of somatostatin-immunoreactive polypeptides. The multiplicity of the preprosomatostatin molecules was the result of initiation of translation from separate species of mRNA as demonstrated by amino-terminal labeling with N-formyl-[35S]Met-tRNAMetf. Translation of islet mRNA isolated from different individual animals showed that all of the preposomatostatin polypeptides were present amongst the cell-free products, which implies that the multiple forms were not due to genetic variation in the wild population. Based on their apparent molecular weights and distinctly different isoelectric points, the different preprosomatostatin molecules could be classified into two major families. These results suggest that the anglerfish preprosomatostatins are encoded by separate mRNA species and are consistent with the existence of a multigene family for somatostatin.
 ...
PMID:Cell-free biosynthesis of somatostatin precursors: Evidence for multiple forms of preprosomatostatin. 612 73

We have previously shown that stimulation of the preganglionic cervical sympathetic trunk leads to an acute increase in tyrosine hydroxylase (TyrOHase) activity in the rat superior cervical ganglion. This increase appears to be mediated in part by acetylcholine and in part by a second neurotransmitter. As a first step in an attempt to determine the identity of this noncholinergic transmitter, we have examined the ability of a number of neuropeptides to increase ganglionic TyrOHase activity in vitro. Secretin and vasoactive intestinal peptide (VIP) both stimulated TyrOHase activity, whereas angiotensin II, bombesin, bradykinin, cholecystokinin octapeptide, glucagon, insulin, luteinizing hormone-releasing hormone, [D-Ala(2), Met(5)]enkephalinamide, motilin, neurotensin, somatostatin, and substance P produced no effects. Secretin produced a significant increase in TyrOHase activity at 1 nM and a maximal elevation at 0.1 muM. VIP produced a significant increase at 0.1 muM and a near maximal effect at 10 muM. Although secretin was about 2 orders of magnitude more potent than VIP, it produced a significantly smaller maximal increase in enzyme activity. Incubation of ganglia with both secretin (10 muM) and VIP (10 muM) produced an increase in TyrOHase activity that was not significantly different from that produced by VIP alone. The stimulatory effects of secretin and VIP were reversible within minutes after removal of the peptides. Neither incubation of intact ganglia with the cholinergic antagonists hexamethonium and atropine nor prior decentralization of ganglia altered the response to the peptides. Thus, the data demonstrate that secretin and VIP acutely increase TyrOHase activity in the superior cervical ganglion and suggest that they produce this effect by acting directly on ganglionic neurons. It remains to be determined whether secretin or VIP or a related peptide is released during preganglionic nerve firing and whether one or more of these peptides is responsible for the noncholinergic elevation of TyrOHase activity produced by preganglionic nerve stimulation.
 ...
PMID:Secretin and vasoactive intestinal peptide acutely increase tyrosine 3-monooxygenase in the rat superior cervical ganglion. 613 May 26

Somatostatin-like immunoreactivity (SLI) from bovine retina was purified and its structure determined. Retinal tissue (1868 g) extracted with 3% acetic acid yielded 18.6 nmol SLI. This peptide was purified by chromatography on an affinity column made with anti-somatostatin antiserum, a reverse-phase C-18 HPLC column, and three sequential applications on a reverse-phase phenyl HPLC column. The peptide was purified 103,000-fold from the initial extract with an overall yield of 14.4%. Amino acid sequence determination by an automatic Edman degradation technique revealed the sequence to be as follows: Ser-Ala-Asn-Ser-Asn-Pro-Ala-Met- Ala-Pro-Arg-Glu-Arg-Lys-Ala-Gly-(Cys)-Lys- Asn-Phe-Phe-Trp-Lys-Thr-(Phe, Thr, Ser, Cys). The apparent identity of this peptide with somatostatin octacosapeptide (S28) purified from other mammalian tissue indicates the phylogenetic conservation of its structure and facilitates the use of the retina as a model system for studying the neurotransmitter function of somatostatin.
 ...
PMID:Structure of somatostatin isolated from bovine retina. 613 55

The 22-residue somatostatin (SST-22) from channel catfish, purified by an improved method, is shown to be a glycopeptide. This represents the first report of a glycosylated somatostatin. Multiple forms of SST-22 exist with the major form containing 1 mol of galactose and 1 mol of N-acetylgalactosamine/mol of peptide attached via an O-glycosidic linkage to Thr-5. The position of the carbohydrate was determined by trapping the reactive peptide following beta-elimination of the carbohydrate with [35S]beta-mercaptoethanol followed by sequencing of the radiolabeled protein. All forms of SST-22 that have been purified are identical in amino acid composition. The heterogeneity resides in the carbohydrate portion of the glycopeptide with at least one of the minor forms containing sialic acid. The sequence for SST-22 obtained by automated Edman degradation is Asp X Asn X Thr X Val X Thr X Ser X Lys X Pro X Leu X Asn X Cys X Met X Asn X Tyr X Phe X Trp X Lys X Ser X Arg X Thr X Ala X Cys. This sequence differs at positions 5 and 19 from that published by Oyama et al. (Oyama, H., Bradshaw, R. A., Bates, O.J., and Permutt, A. (1980) J. Biol. Chem. 255, 2251-2254). The amino acid sequence reported here is identical to that deduced from the cDNA. The mass ion of SST-22 was determined by fast atom bombardment/mass spectrometry and shown to be 2943 +/- 1 (m/z). The observed mass ion is consistent with the molecular weight predicted from the amino acid sequence plus 1 mol of galactose and 1 mol of N-acetylgalactosamine.
 ...
PMID:Structure of the 22-residue somatostatin from catfish. An O-glycosylated peptide having multiple forms. 614 20

Six peptides from an extract of a human pancreatic tumour were purified to homogeneity by HPLC. Amino acid composition and chemical properties indicated probable structures the same as somatostatin-14, somatostatin-28 (1-12), [Met(O)8]somatostatin-28 (1-12), [Met(O)8]somatostatin-28 (1-10), somatostatin-25 (1-9) and [Met(O)5]somatostatin-25 (1-9). The structure of somatostatin-14 was confirmed by sequence analysis. The isolation of these peptides provides insight into the processing of prosomatostatin in the tumour cells.
 ...
PMID:Fragments of prosomatostatin isolated from a human pancreatic tumour. 615 29

The demonstration of depolarization-induced release of substance P, Met- and Leu-enkephalin, somatostatin, neurotensin, vasoactive intestinal polypeptide and cholecystokinin-like material from various regions of rat brain in vitro supports the hypothesis that these and other neuropeptides may act as neurotransmitters. In each case the stimulus-evoked release, but not the basal release, of peptide was dependent on the presence of calcium ions in the external medium. The stimulus-evoked release of substance P from nerve terminals in rat substantia nigra may be regulated by presynaptic gamma-aminobutyric acid (GABA) receptors. The possible existence of presynaptic opiate receptors on substance P-containing sensory nerve terminals may offer an explanation for the analgesic effects of opiates at spinal cord level, and for the existence of enkephalin neurons in substantia gelatinosa. Capsaicin releases substance P from spinal cord nerve terminals and may impair their function, while having no effect on substance P neurons in supraspinal regions. The possibility of cosecretion of peptide and amine products from the same cells is discussed.
 ...
PMID:Regulation of neuropeptide release. 615 55

Receptors for thyrotropin-releasing hormone (TRH) on membranes of rat spinal cord (SC) were labeled with [3H](3-Me-His2)TRH ([3H]MeTRH) (dissociation constant = 3.6 +/- 0.8 (6) nM). Substance P (SP) caused a concentration-dependent inhibition of TRH receptor binding in the micromolar range (43 +/- 4 (6)% at 50 microM). Scatchard analyses of competition data revealed that 50 microM SP reduced TRH receptor number (40-66%, P less than 0.05) with little or no effect on affinity. SP appeared more potent in reducing [3H]MeTRH binding to ventral cord membranes than those of dorsal or whole SC. A number of SP analogs also reduced TRH receptor binding in a dose-related manner but with different potencies. In contrast, various amino acids and serotonin (250 microM) produced little or no inhibition of [3H]MeTRH binding, and cholecystokinin, Leu- and Met-enkephalins, angiotensin II, LH-RH, bombesin and somatostatin were also markedly less potent than SP. Although it is unclear whether spinal TRH receptors are ever exposed to micromolar concentrations of SP in vivo, the reported colocalization of these neuropeptides in raphe efferents to the SC suggests that our findings may be of physiological relevance.
 ...
PMID:Micromolar substance P reduces spinal receptor binding for thyrotropin-releasing hormone--possible relevance to neuropeptide coexistence? 620 Aug 6

Within the physiological range of other known releasing factors, human pancreatic tumor growth hormone releasing factor (hpGRF) is specific for GH release. Data concerning hpGRF action on cAMP and GH are consistent with the concept of cAMP acting as a second messenger for this releasing factor. hpGRF-stimulated GH release is Ca++ dependent. Exogenous hpGRF40 does not alter the interdigestive gastric motility or secretion of gastrin and motilin in dogs, while large doses of hpGRF stimulate somatostatin release into the hepatic portal blood of the rat. Significant GRF activity as determined by a rat pituitary perifusion system is confined within the median eminence and the arcuate nucleus, though detectable but insignificant GRF activity is present in other area of the hypothalamus and cortex in the rat. GRF activity is present in the ovine brain as well as in the gut. Both tissues contain large (between 4000-5000 daltons) and small (but possibly larger than 1000 daltons) m.w. GRF materials. GRF appears to be structurally different between species and more than one GRF may be present within the same species. One of the ovine brain peptides with GH-releasing activity was partially characterized as His-Ser-Asp-Gly-Ile-Phe-Thr-Asp-Ser-Tyr- Lys-Arg-Try-Asn-Lys-Glu-Met- Ala-Lys--which is similar to rat GRF and porcine VIP having His at the N-terminus. Another peptide with GRF activity which eluted earlier on reverse phase HPLC and later on cation exchange chromatography has also been obtained in a pure form.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Growth hormone releasing factors in the brain and the gut: chemistry, actions, and localization. 620 12

The importance of nerve growth factor (NGF) for the development of sensory ganglia was investigated by injecting rat fetuses (16.50 days of gestation) with a single dose of anti-NGF antiserum. Four months later the treated animals showed a very large decrease in substance P- and somatostatin-like immunoreactivities in dorsal root ganglia and skin with a lesser decrease in trigeminal ganglia. Fluoride-resistant acid phosphatase, substance P-, and somatostatin-like immunoreactivities were greatly decreased in the dorsal horn of the spinal cord. No change in neurotensin- and [Met]enkephalin-like immunoreactivities was observed. The anti-NGF antiserum treatment produced a greater than 90% decrease in the number of unmyelinated dorsal root fibers and a 35% decrease in the total number of myelinated fibers. The loss in myelinated fibers was restricted to small-diameter fibers with no change in large-diameter fibers. No change in taste bud morphology was noted, thereby refuting the proposal that anti-NGF antiserum treatment may represent an animal model for familial dysautonomia. The present results indicate that NGF is a necessary requirement for the normal development of a significant population of prenatal rat dorsal root ganglion cells.
 ...
PMID:Biochemical and anatomical effects of antibodies against nerve growth factor on developing rat sensory ganglia. 660 28

Analysis of peptides by reverse-phase high-pressure liquid chromatography would be simplified if retention times could be predicted by summing the contribution to retention of each of the peptide's amino acid side chains. This paper describes the derivation of values ("retention coefficients") that represent the contribution to retention of each of the common amino acids and end groups. Peptide retention times were determined on a Bio-Rad "ODS" column at room temperature with a linear gradient from 0.1 M NaclO(4), pH 7.4 or 2.1, at 0 min to 60% acetonitrile/0.1 M NaclO(4) at 80 min. The NaclO(4), a chaotropic agent, was added to improve peak shape and to minimize conformational effects. Retention coefficients for the amino acids were computed by using a Hewlett-Packard 9815A calculator programmed to change the retention coefficients for all amino acids sequentially to obtain a maximum correlation between actual and predicted retention times. Correlations of 0.999 at pH 7.4 and 0.997 at pH 2.1 were obtained for 25 peptides including glucagon, oxytocin, [Met]enkephalin, neurotensin, and somatostatin. This high degree of correlation suggests that, for peptides containing up to 20 residues, retention is primarily due to partition processes that involve all the residues. Although steric or conformational factors do have some effect on retention, the data suggest that under the above chromatographic conditions the retention of peptides containing up to 20 residues can be predicted solely on the basis of their amino acid composition. This possibility was tested by using data taken from the literature.
 ...
PMID:Prediction of peptide retention times in high-pressure liquid chromatography on the basis of amino acid composition. 692 13


<< Previous 1 2 3 4 5 6 7 8 9 Next >>