| 8100352 |
Cloning and expression of a human somatostatin-14-selective receptor variant (somatostatin receptor 4) located on chromosome 20. |
10.1006/bbrc.1993.2122 |
Mol. Pharmacol. |
Cloning and expression of a human somatostatin-14-selective receptor variant (somatostatin receptor 4) located on chromosome 20.
Abstract
- Based on pharmacological, biochemical, and molecular criteria, multiple somatostatin receptor (SSTR) subtypes selective for somatostatin (SST)-14 and -28 have been postulated to exist in both the brain and periphery. We report here on the cloning and characterization of a human gene encoding a new member of the guanine nucleotide-binding protein-linked SSTR family, termed human (h)SSTR4. The 388-amino acid protein, with a predicted molecular mass of approximately 42 kDa, displays sequence similarity, particularly within putative transmembrane domains, with the recently cloned hSSTR1 (69%), hSSTR2 (56%), and hSSTR3 (58%). Membranes prepared from COS-7 cells transiently expressing the hSSTR4 gene bound 125I-[Leu8,D-Trp22,Tyr25]SST-28 in a saturable manner with high affinity (approximately 60 pM) and with a pharmacological profile and rank order of potency ([D-Trp8]SST-14 > SST-14 > SMS 201-995 > SST-28 > MK-678) indicative of a SST-14-selective receptor. Ki values for the inhibition of 125I-[Leu8,D-Trp22,Tyr25]SST-28 binding to the expressed receptor by these somatostatinergic peptides were 0.3, 1.1, 1.4, 2.2, and 6.5 nM, respectively. High affinity agonist binding to hSSTR4 was significantly reduced by GTP and pertussis toxin, indicating association of the expressed receptor with pertussis toxin-sensitive guanine nucleotide-binding proteins. Northern blot analysis revealed the presence of an SSTR4 mRNA species of approximately 4 kilobases in select regions of the monkey brain, including the hippocampus, hypothalamus, cortex, and striatum, with little or no receptor mRNA detected in either the olfactory tubercle, medulla, cerebellum, or amygdala. The SSTR4 gene maps to human chromosome 20. These findings document the existence of a novel human SSTR gene. Although the hSSTR4 displays an overall deduced amino acid homology of 86% with the recently reported rat homolog [Proc. Natl. Acad. Sci. USA 89:11151-11155 (1992)], the two gene products possess distinctive pharmacological profiles and affinities for the SST agonists SMS 201-995 and MK-678.
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| 8105412 |
Effects of new somatostatin analogs on the cell proliferation of colonic crypts and colonic cancers in rats |
10.1016/0143-4179(93)90069-m. |
Neuropeptides |
Effects of new somatostatin analogs on the cell proliferation of colonic crypts and colonic cancers in rats
Abstract
- The antiproliferative activity of two new somatostatin (SS) analogs: ASS-51 and ASS-52 have been tested in this study. We assessed their ability to inhibit the DNA synthesis in normal colon crypt cells and in the cells of chemically (dimethylhydrazine)-induced colon cancer in the rats. The incorporation of bromodeoxyuridine (BrDU) into appropriate cell nuclei was used as an index of DNA synthesis. It was found that: 1) Only ASS-51 significantly decreases the colon crypt cell proliferation in the rat when compared to controls. Since both analogs were previously shown to inhibit GH release, these data indicate that the antiproliferogenic effect of ASS-51 is independent of the inhibition of GH release. 2) Both examined analogs did not significantly effect the BrDU incorporation into cell nuclei of chemically-induced colon cancer.
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| 8111128 |
Molecular cloning and chromosomal localization of a human skeletal muscle PP-1 gamma 1 cDNA. |
10.1007/bf00360567 |
Mamm. |
Molecular cloning and chromosomal localization of a human skeletal muscle PP-1 gamma 1 cDNA.
Abstract
- Type-1-protein phosphatase (PP-1) activity is reduced in skeletal muscle from human subjects with insulin resistance (Kida et al. 1990). This reduced phosphatase activity probably leads to the abnormal insulin action for glucose storage observed in insulin-resistant subjects. In the present study, a human homolog of rat liver PP-1 gamma 1 cDNA was isolated from human skeletal muscle. The nucleotide sequence contains a 957-nucleotide open reading frame encoding an amino acid sequence identical to that encoded by rat liver PP-1 gamma 1 cDNA. Northern blot analysis shows PP-1 gamma 1-specific mRNA is expressed in human heart, brain, placenta, lung, liver, skeletal muscle, kidney, and pancreas. PP-1 gamma 1 was localized to human Chromosome 12.
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| 8132570 |
A point mutation leads to an unpaired cysteine residue and a molecular weight polymorphism of a functional platelet beta 3 integrin subunit. The Sra alloantigen system of GPIIIa |
None |
J Biol Chem |
A point mutation leads to an unpaired cysteine residue and a molecular weight polymorphism of a functional platelet beta 3 integrin subunit. The Sra alloantigen system of GPIIIa
Abstract
- Recently, we described a low frequency platelet alloantigen on human platelet membrane glycoprotein (GP) IIIa, termed Sra, that was involved in neonatal alloimmune thrombocytopenia. To identify the molecular nature of the Sra alloantigen, we analyzed the nucleotide sequence of polymerase chain reaction-amplified GPIIIa mRNA, and found a C2004-->T substitution in seven Sra positive individuals which results in an Arg636-->Cys polymorphism within the cysteine-rich region of GPIIIa. Analysis of allele-specific recombinant forms of GPIIIa that differed only at amino acid residue 636 showed that anti-Sra alloantibodies reacted with the Cys636, but not the Arg636, recombinant form of GPIIIa. Interestingly, under reducing conditions, the Cys636 form of GPIIIa migrated with a slightly increased apparent molecular weight compared with the Arg636 form. Following treatment with Endoglycosidase H, both allelic forms of GPIIIa exhibited the same mobility, however the Sra epitope was lost. Sra positive platelets express the same number of GPIIb-IIIa complexes on their surface as wild-type Sra negative platelets, and also aggregate normally in response to a variety of platelet agonists. Based upon these results, we conclude that 1) GPIIIa residue 636 specifically controls the formation and expression of the Sra alloantigenic determinant, and 2) an unpaired cysteine residue alters the N-linked glycosylation pattern of the extracellular domain of GPIIIa, but affects neither the degree of surface expression nor the adhesive function of the GPIIb-IIIa complex.
|
| 8134423 |
Suppressive effects of metabolites from Alternaria brassicaea on the hepatitis B surface antigen |
10.1055/s-2006-959416. |
Planta Med |
Suppressive effects of metabolites from Alternaria brassicaea on the hepatitis B surface antigen
Abstract
|
| 8143880 |
An isoform of the human calcitonin receptor is expressed in TT cells and in medullary carcinoma of the thyroid. |
10.1016/0014-5793(94)80503-2 |
FEBS Lett. |
An isoform of the human calcitonin receptor is expressed in TT cells and in medullary carcinoma of the thyroid.
Abstract
- We amplified, using the polymerase chain reaction and calcitonin receptor (CTR) specific primers, RNA extracted from medullary thyroid carcinoma (MTC) and the derived TT cell line. Both secrete large amounts of calcitonin. Electrophoresis of amplification products revealed, in both cases, an ethidium bromide-stained band that hybridized to a CTR probe. Sequencing the band amplified from TT cells revealed an open reading frame identical to the sequence of H-CTR but lacking 16 amino acids in the first intracellular loop. This demonstrates the existence of an mRNA coding for a subtype of H-CTR which is expressed in TT cells and MTC.
|
| 8144591 |
Recombinant human betacellulin. Molecular structure, biological activities, and receptor interaction |
None |
J Biol Chem |
Recombinant human betacellulin. Molecular structure, biological activities, and receptor interaction
Abstract
- Soluble forms of human betacellulin (BTC) were purified to homogeneity from the conditioned medium of mouse A9 cells transfected with the BTC precursor cDNA. Three types of soluble BTC, designated BTC-1a, BTC-1b and BTC-2, were resolved by cation-exchange and size-exclusion column chromatography. Physicochemical analysis has revealed that BTC-1a represents the glycosylated, intact molecule composed of 80 amino acid residues (Asp32 to Tyr111 of the precursor molecule). BTC-1b appears to be a truncated molecule lacking 12 amino acid residues from the amino terminus of BTC-1a. BTC-2 was found to be a 50-amino acid molecule (Arg62 to Tyr111) that corresponds to the epidermal growth factor (EGF) structural unit. The biological activities of these BTC molecules were essentially identical as judged by their mitogenicity on Balb/c 3T3 fibroblasts. BTC and EGF were equipotent in stimulating Balb/c 3T3 cell proliferation and rat mesangial cell Ca2+ mobilization as well as in inhibiting the growth of human epidermoid carcinoma A431 cells. BTC and EGF antagonized each other with similar dose dependence for binding to A431 cells, indicating that these factors bind the same receptor molecules with equivalent avidity. The Kd value of EGF receptor (EGFR) and BTC is 0.5 nM as determined on Balb/c 3T3 cells. In addition, human mammary carcinoma MDA-MB-453 cells, which express multiple members of the EGFR family, were found to possess 2.7 x 10(3) BTC binding sites/cell, and the binding was readily quenched by EGF. These results suggest that the primary receptor for BTC is EGFR.
|
| 8144672 |
Ranalexin. A novel antimicrobial peptide from bullfrog (Rana catesbeiana) skin, structurally related to the bacterial antibiotic, polymyxin |
None |
J Biol Chem |
Ranalexin. A novel antimicrobial peptide from bullfrog (Rana catesbeiana) skin, structurally related to the bacterial antibiotic, polymyxin
Abstract
- Antimicrobial peptides comprise a diverse class of molecules used in host defense by plants, insects, and animals. In this study we have isolated a novel antimicrobial peptide from the skin of the bullfrog, Rana catesbeiana. This 20 amino acid peptide, which we have termed Ranalexin, has the amino acid sequence: NH2-Phe-Leu-Gly-Gly-Leu-Ile-Lys-Ile-Val-Pro-Ala-Met-Ile-Cys-Ala-Val-Thr- Lys-Lys - Cys-COOH, and it contains a single intramolecular disulfide bond which forms a heptapeptide ring within the molecule. Structurally, Ranalexin resembles the bacterial antibiotic, polymyxin, which contains a similar heptapeptide ring. We have also cloned the cDNA for Ranalexin from a metamorphic R. catesbeiana tadpole cDNA library. Based on the cDNA sequence, it appears that Ranalexin is initially synthesized as a propeptide with a putative signal sequence and an acidic amino acid-rich region at its amino-terminal end. Interestingly, the putative signal sequence of the Ranalexin cDNA is strikingly similar to the signal sequence of opioid peptide precursors isolated from the skin of the South American frogs Phyllomedusa sauvagei and Phyllomedusa bicolor. Northern blot analysis and in situ hybridization experiments demonstrated that Ranalexin mRNA is first expressed in R. catesbeiana skin at metamorphosis and continues to be expressed into adulthood.
|
| 8145226 |
Conformationally constrained peptides and semipeptides derived from RGD as potent inhibitors of the platelet fibrinogen receptor and platelet aggregation |
10.1021/jm00032a009. |
J Med Chem |
Conformationally constrained peptides and semipeptides derived from RGD as potent inhibitors of the platelet fibrinogen receptor and platelet aggregation
Abstract
- Structure-activity studies have been pursued on cyclo-S,S-Ac-Cys-(N alpha-Me)Arg-Gly-Asp-Pen-NH2, 2 (SK&F 106760), a potent inhibitor of platelet aggregation, in an effort to improve potency and affinity for the GPIIb/IIIa receptor. Modifications on the N- and C-termini of 2 produced a series of peptides which indicate that the C-terminal carboxylate group may be a secondary receptor-binding element. Further modification by replacing the disulfide tether N alpha-acetylcysteine/penicillamineamide with the novel, inexpensive, achiral, constrained, and more lipophilic tether 2-mercaptobenzoyl/2-mercaptoaniline (Mba/Man) afforded the semipeptide cyclo-S,S-Mba-(N alpha-Me)Arg-Gly-Asp-Man, 18 (SK&F 107260), which exhibited significant enhancement in both affinity and potency. To further investigate the effect of the phenyl ring at the C-terminus, peptides bearing the novel (2R,3S)- and (2R,3R)-beta-phenylcysteines were synthesized, which culminated in the cyclo-S,S-Ac-Cys-(N alpha-Me)Arg-Gly-Asp-(2R,3S)-beta-phenylCys-OH peptide, 22, which displayed substantial affinity and potency. We describe, herein, the development of both 18 and 22 and the additional structural modifications within the constrained cyclic disulfide ring to probe the stereochemical and steric requirements for receptor interaction.
|
| 8146160 |
Cytolytic and antibacterial activity of synthetic peptides derived from amoebapore, the pore-forming peptide of Entamoeba histolytica |
10.1073/pnas.91.7.2602. |
Proc Natl Acad Sci U S A |
Cytolytic and antibacterial activity of synthetic peptides derived from amoebapore, the pore-forming peptide of Entamoeba histolytica
Abstract
- The pore-forming peptide amoebapore is considered part of the cytolytic armament of pathogenic Entamoeba histolytica. Amoebapore is composed of 77 amino acid residues arranged in four alpha-helical domains. For structure-function analysis, synthetic peptides were constructed corresponding to these four domains: H1 (residues 1-22), H2 (25-39), H3 (40-64), and H4 (67-77). The peptides H1 and H3, representing two highly amphipathic alpha-helical regions of amoebapore, possessed pore-forming activity. Peptide H3 displayed cytolytic and antibacterial functions similar to those of natural amoebapore. The most potent antibacterial activity and the broadest activity spectrum were expressed by H1-Mel, a hybrid molecule composed of the N-terminal alpha-helix of amoebapore and the C-terminal hexapeptide of melittin from the venom of Apis mellifera.
|
| 8154520 |
Platelet GPIIb/IIIa antagonists: how safe is this antithrombotic approach? |
10.1016/0002-9343(94)90159-7. |
Am J Med |
Platelet GPIIb/IIIa antagonists: how safe is this antithrombotic approach?
Abstract
|
| 8155814 |
Calculation of the circular dichroism spectrum of cyclo-(L-tyr-L-tyr) based on a molecular dynamics simulation |
10.1016/0301-4622(93)e0065-d. |
Biophys Chem |
Calculation of the circular dichroism spectrum of cyclo-(L-tyr-L-tyr) based on a molecular dynamics simulation
Abstract
- Theoretical calculations of CD spectra have generally assumed a single conformation, or a small number of conformers with Boltzmann averaging. Solvent effects on both the conformation and the CD have been neglected. In this work, we have calculated the CD spectrum of cyclo(L-Tyr-L-Tyr) in aqueous solution, taking dynamics and solvation into account. Starting geometries with chi 1 approximately 300 degrees or 60 degrees for both Tyr side chains were derived from MNDO/MOPAC, followed by energy minimization using GROMOS. After addition of 368 water molecules, the system was simulated for 1000 ps at 300 K using GROMOS. In addition to the starting conformer, two other conformers were observed during each simulation. However, each trajectory gave a distinct set of conformers. Rotational strengths were calculated for the cyclic dipeptide at each ps along the trajectories, using the matrix method. The CD spectra calculated from these rotational strengths were averaged over the trajectories. Agreement is very good for the strong negative band near 200 nm, while for the lower energy bands (near 230 and 280 nm), the signs are correct, but the magnitudes are too low. The spectrum calculated from a Boltzmann-weighted average over the in vacuo MNDO/MOPAC conformers was in poor agreement with experiment. Although the solvent did not significantly affect the rotational strength calculated for a given conformer, it is essential to include the solvent in the MD simulations because it affects the relative energies of the conformers and promotes transitions among them.
|
| 8163497 |
Antimicrobial peptides from skin secretions of Rana esculenta. Molecular cloning of cDNAs encoding esculentin and brevinins and isolation of new active peptides |
None |
J Biol Chem |
Antimicrobial peptides from skin secretions of Rana esculenta. Molecular cloning of cDNAs encoding esculentin and brevinins and isolation of new active peptides
Abstract
- Three cytolytic peptides, termed brevinin-1E, brevinin-2E, and esculentin, were isolated from skin secretions of the European frog Rana esculenta (Simmaco, M., Mignogna, G., Barra, D., and Bossa, F. (1993) FEBS Lett. 324, 159-161). Nucleotide sequence analysis of cDNAs coding for the corresponding precursors revealed that in all of them a single copy of the sequence of the mature peptide is present preceded by a dibasic cleavage site and followed by a stop codon. The signal peptides of these precursors show a clear homology to the corresponding region of the precursor of dermorphin, a neuropeptide occurring in the skin of amphibians of the subfamily Phyllomedusinae. Ten new peptides, ranging in size from 24 to 46 residues, all possessing an intramolecular disulfide bridge located at the carboxyl-terminal end, were isolated from skin secretions of R. esculenta. These peptides can be grouped into four subfamilies on the basis of their distinctive structural and/or functional properties. All of these new peptides have antimicrobial and/or hemolytic activities typical for the respective subfamily. In addition, we demonstrate that esculentin-1 also inhibits the growth of Pseudomonas aeruginosa, Candida albicans, and Saccharomyces cerevisiae.
|
| 8163526 |
Chemical and genetic characterization of bacteriocins produced by Carnobacterium piscicola LV17B |
None |
J Biol Chem |
Chemical and genetic characterization of bacteriocins produced by Carnobacterium piscicola LV17B
Abstract
- Carnobacteriocins BM1 and B2 are thermostable class II bacteriocins produced by Carnobacterium piscicola LV17B. These bacteriocins were purified by a three-step procedure that included hydrophobic interaction, size exclusion, and reversed-phase high performance liquid chromatography. The purified peptides and fragments derived by enzymatic digestion were analyzed by Edman degradation, amino acid analysis, and mass spectrometry. An oxidized form of carnobacteriocin BM1 (carnobacteriocin B1) was also purified and characterized. Probes synthesized using information from the N-terminal amino acid sequences for the purified bacteriocins were used to locate structural genes for the carnobacteriocins. A 1.9-kilobase (kb) HindIII fragment from a 61-kb plasmid (pCP40) containing the carnobacteriocin B2 structural gene and a 4.0-kb EcoRI-PstI genomic fragment containing the carnobacteriocin BM1 structural gene were cloned and fully or partially sequenced, respectively. Expression of the chromosomal bacteriocin and its immunity function requires the presence of the 61-kb plasmid. The results indicate that both bacteriocins are synthesized as prebacteriocins. Post-translational cleavage of an 18-amino acid N-terminal extension at a Gly-Gly (positions -2 and -1) site takes place in each prepeptide to yield the mature 43-amino acid carnobacteriocin BM1 (molecular mass 4524.6) and the mature 48-amino acid carnobacteriocin B2 (molecular mass 4969.9). These two peptides showed significant amino acid homology to each other and with those class II bacteriocins which contain the YGNGV amino acid motif near the N terminus.
|
| 8164255 |
Cyclic beta-casomorphin analogues with mixed mu agonist/delta antagonist properties: synthesis, pharmacological characterization, and conformational aspects |
10.1021/jm00034a011. |
J Med Chem |
Cyclic beta-casomorphin analogues with mixed mu agonist/delta antagonist properties: synthesis, pharmacological characterization, and conformational aspects
Abstract
- Analogues of the potent and moderately mu-opioid-receptor-selective cyclic beta-casomorphin-5 derivative H-Tyr-c-D-Orn-Phe-D-Pro-Gly- (2) were prepared by conventional solution synthesis. Replacement of the Phe3 residue by 2-naphthylalanine (2-Nal) led to a peptide (4) with high affinity for both mu and delta opioid receptors. This compound turned out to be an agonist in the mu-receptor-representative guinea pig ileum (GPI) assay but a moderately potent antagonist against various delta agonists in the delta-receptor-representative mouse vas deferens (MVD) assay. It thus represents the first known cyclic opioid peptide analogue with mixed mu agonist/delta antagonist properties. Interestingly, replacement of 2-Nal3 in compound 4 with 1-naphthylalanine (1-Nal) resulted in an analogue (5) showing high affinity for mu receptors and a full agonist effect in the MVD assay that was mediated by both mu and delta receptors. Substitution of Trp for Phe3 in 2 (compound 8) was well tolerated at both receptors and led to an analogue with agonist activity in both the GPI and MVD assays. Variation of the peptide ring size in 4 was achieved by substitution of D-Orn2 with D-Lys (compound 6) or D-2,4-diaminobutyric acid (compound 7). Analogue 6 was also a mixed mu agonist/delta antagonist with somewhat lower potency than 4, whereas compound 7 displayed mu agonist and partial delta agonist properties. Further reduction of the peptide ring size, as achieved by deletion of the Gly5 residue, produced a compound (9) which was a full agonist in both bioassays. Conformational analysis of analogues 2, 4, and 5 by 1H NMR spectroscopy and molecular mechanics studies suggested that the overall conformation of parent compound 2 and the 2-Nal-containing peptide 4 was similar, while the side-chain orientation of 1-Nal in peptide 5 was different. These results suggest that the delta antagonist properties of analogue 4 may not be due to a difference in its overall conformation as compared to the agonist 2 but may be a direct effect of the 2-naphthyl moiety per se preventing proper alignment of the peptide for receptor activation.
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