| 3059494 |
Human insulin-degrading enzyme shares structural and functional homologies with E. coli protease III. |
10.1126/science.3059494 |
Science |
Human insulin-degrading enzyme shares structural and functional homologies with E. coli protease III.
Abstract
- A proteinase with high affinity for insulin has been proposed to play a role in the cellular processing of this hormone. A complementary DNA (cDNA) coding for this enzyme has been isolated and sequenced. The deduced amino acid sequence of the enzyme contained the sequences of 13 peptides derived from the isolated protein. The cDNA could be transcribed in vitro to yield a synthetic RNA that in cell-free translations produced a protein that coelectrophoresed with the native proteinase and could be immunoprecipitated with monoclonal antibodies to this enzyme. The deduced sequence of this proteinase did not contain the consensus sequences for any of the known classes of proteinases (that is, metallo, cysteine, aspartic, or serine), but it did show homology to an Escherichia coli proteinase (called protease III), which also cleaves insulin and is present in the periplasmic space. Thus, these two proteins may be members of a family of proteases that are involved in intercellular peptide signaling.
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| 3078280 |
Dihydrocyclosporin D in sheep: haemodynamic and renal effects |
10.1111/j.1440-1681.1988.tb01095.x. |
Clin Exp Pharmacol Physiol |
Dihydrocyclosporin D in sheep: haemodynamic and renal effects
Abstract
- 1. This study was designed to test the haemodynamic and renal effects in sheep of dihydrocyclosporin D (dCyD), an immunosuppressant agent derived from the fungus Tolypocladium inflatum Gams. 2. dCyD was infused for 5 days at 12 mg/kg per day. Mean arterial pressure (MAP) was elevated after 24 h, but thereafter returned to control levels. Heart rate was significantly elevated throughout the infusion and was still high 24 h postinfusion. Cardiac output rose after 5 days, but total peripheral resistance was unchanged during the infusion. 3. Glomerular filtration rate, renal blood flow and effective renal plasma flow remained unchanged, although urine sodium excretion rose for the first 48 h. 4. Infusion of the castor oil-based vehicle for cyclosporin, Cremaphore EL, for 5 days in four sheep did not produce any sustained changes in any of the parameters measured.
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| 3101064 |
Replacement of lysine residue 1030 in the putative ATP-binding region of the insulin receptor abolishes insulin- and antibody-stimulated glucose uptake and receptor kinase activity. |
10.1073/pnas.84.3.704 |
Proc. Natl. Acad. Sci. U.S.A. |
Replacement of lysine residue 1030 in the putative ATP-binding region of the insulin receptor abolishes insulin- and antibody-stimulated glucose uptake and receptor kinase activity.
Abstract
- To test whether the tyrosine kinase activity of the insulin receptor is crucial for insulin action, we have constructed mutations of the human insulin receptor at Lys-1030, which is in the presumed ATP-binding region. By using oligonucleotide-directed mutagenesis, this lysine residue was replaced with either methionine, arginine, or alanine. Chinese hamster ovary cells were transfected by mutant cDNAs and the expressed insulin receptors were characterized. We show here that none of these mutants exhibited insulin-activated autophosphorylation and kinase activity in vitro. They also do not mediate insulin- and antibody-stimulated uptake of 2-deoxyglucose. The tyrosine kinase activity is thus required for a key physiological response of insulin.
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| 3106287 |
Effect of amino acids on the biosynthesis of beta-amino acids, constituents of bacillomycins F |
10.7164/antibiotics.40.221. |
J Antibiot (Tokyo) |
Effect of amino acids on the biosynthesis of beta-amino acids, constituents of bacillomycins F
Abstract
|
| 3123509 |
Liquid chromatographic determination of the cyanoginosins, toxins produced by the cyanobacterium Microcystis aeruginosa |
10.1016/s0021-9673(01)81837-9. |
J Chromatogr |
Liquid chromatographic determination of the cyanoginosins, toxins produced by the cyanobacterium Microcystis aeruginosa
Abstract
|
| 3124301 |
Preparation of a beta-amanitin-concanavalin A conjugate of low toxicity |
10.1016/0041-0101(87)90161-9. |
Toxicon |
Preparation of a beta-amanitin-concanavalin A conjugate of low toxicity
Abstract
- Pure beta-amanitin was isolated by combined adsorption chromatography of a crude methanol extract from Amanita phalloides on Sephasorb HP Ultrafine and Sephadex LH-20. The beta-amanitin was coupled to concanavalin A by the carbodiimide method. The conjugate was purified by fractionation on a column of Sephadex G-75. The molar ratio beta-amanitin to concanavalin A in this conjugate was 4.14. The purified conjugate was tested by thin-layer chromatography and showed characteristic (for amatoxins) bright purple staining but different mobility. The ultraviolet spectrum of the conjugate was different from the spectra of the native beta-amanitin and the native concanavalin A. The toxicity of the conjugate was determined by in vivo toxicological studies and was four-fold lower than that of the native beta-amanitin. These results suggest that this conjugate may be used for immunization procedures and for the production of amatoxin-specific antibodies.
|
| 3130364 |
Bacillomycins Fb and Fc: isolation and characterization |
10.7164/antibiotics.41.282. |
J Antibiot (Tokyo) |
Bacillomycins Fb and Fc: isolation and characterization
Abstract
- Bacillomycins Fb and Fc, new antifungal antibiotics, were isolated from a strain of Bacillus subtilis producing bacillomycin F. Because of the presence of beta-amino acids, these compounds belong to the iturin group. The acid hydrolysates contained alpha-amino acids Asp3, Glu1, Pro1, Thr1, Tyr1 and a mixture of iso-C15, anteiso-C15, iso-C16, iso-C17 and anteiso-C17 beta-amino acids. The ratios of the different beta-amino acids depend on the nature of the culture medium. Bacillomycins Fb and Fc differ from bacillomycin F by the presence of free carboxyl groups.
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| 3138233 |
Epidermal growth factor receptor threonine and serine residues phosphorylated in vivo. |
10.1016/s0021-9258(18)37684-1 |
J. Biol. Chem. |
Epidermal growth factor receptor threonine and serine residues phosphorylated in vivo.
Abstract
- The epidermal growth factor (EGF) receptor is regulated by EGF-stimulated autophosphorylation and by phorbol ester-stimulated, protein kinase C (Ca2+/phospholipid-dependent enzyme) mediated phosphorylation at identified sites. The EGF receptor contains additional phosphorylation sites including a prominent phosphothreonine and several phosphoserines which account for the majority of phosphate covalently bound to the receptor in vivo. We have identified three of these sites in EGF receptor purified from 32P-labeled A431 cells. The major phosphothreonine was identified as threonine 669 in the EGF receptor sequence. Phosphoserine residues were identified as serines 671 and 1046/1047 of the EGF receptor. Two other phosphoserine residues were localized to tryptic peptides containing multiple serine residues located carboxyl-terminal to the conserved protein kinase domain. The amino acid sequences surrounding the three identified phosphorylation sites are highly conserved in the EGF receptor and the protein products of the v-erb B and neu oncogenes. Analysis of predicted secondary structure of the EGF receptor reveals that all of the phosphorylation sites are located near beta turns. In A431 cells phosphorylation of the serine residues was dependent upon serum. In mouse B82 L cells transfected with a wild type human EGF receptor. EGF increased the 32P content in all tryptic phosphopeptides. A mutant EGF receptor lacking protein tyrosine kinase activity was phosphorylated only at threonine 669. Regulated phosphorylation of the EGF receptor at these threonine and serine residues may influence aspects of receptor function.
|
| 3141403 |
Structure, expression, and evolution of a gene encoding the precursor of nisin, a small protein antibiotic |
None |
J Biol Chem |
Structure, expression, and evolution of a gene encoding the precursor of nisin, a small protein antibiotic
Abstract
- We have cloned and sequenced a gene (spaN) from Streptococcus lactis ATCC 11454 which encodes the peptide precursor of the small protein antibiotic nisin. The encoded precursor is 57 amino acids long, with a 23-residue leader region and a 34-residue structural region. The structural region contains serines, threonines, and cysteines at exactly the positions required to give mature nisin by a series of post-translational modifications involving dehydration of serines and threonines to dehydro forms, and cross-linking with cysteine residues. S1 mapping revealed a 267-nucleotide transcript of the nisin gene that is expressed during vegetative growth and stationary phase. It has a half-life of 7-10 min. The absence of an identifiable promoter or rho-independent terminator and the detection of two different 5'-ends of the transcript suggested it is a processing product from a larger RNA. This may represent a polycistronic mRNA which may also encode proteins involved in processing the nisin precursor peptide. Open reading frames were found in regions flanking the nisin gene. The one downstream had a ribosome binding site and appeared to be transcribed by read-through from the nisin gene. The one upstream had significant homology to a putative transposase from the Escherichia coli IS2 insertion element. Comparison of gene sequence homologies between nisin and the other lanthionine antibiotics, subtilin and epidermin, indicated that they all evolved from a common ancestor. Corresponding leader peptide sequences showed mediocre amino acid homology, but nearly perfect hydropathic homologies, suggesting a common function. It is proposed that this function includes recognition signals or other information required for post-translational processing."
|
| 3158359 |
Fast atom bombardment mass spectrometry of bouvardin and selected analogs |
10.1002/bms.1200120205. |
Biomed Mass Spectrom |
Fast atom bombardment mass spectrometry of bouvardin and selected analogs
Abstract
- The fast atom bombardment (FAB) mass spectra of bouvardin (1) 6-O-methylbouvardin (2), deoxybouvardin (3) and a synthetic analog (4) have been examined. The spectra of the bicyclic compounds 1-3 display site-directed fragmentations resulting from the presence of a phenolic bridged tyrosine moiety unique to this class of compounds. Comparison of the spectrum of 4, which lacks the rigid 14-membered ring, with the spectra of 1-3 shows some similarities, but clearly does not cleave in a site-directed manner as the other bouvardin analogs. Fragmentation pathways are postulated which account for most of the major ions observed in the FAB mass spectra of these potentially useful antitumor agents. Metastable ion analysis confirms the operation of the proposed pathways.
|
| 3165296 |
Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17. |
10.1101/gr.2596504 |
Blood |
Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17.
Abstract
- Platelet aggregation requires the binding of adhesive proteins such as fibrinogen to the heterodimer of membrane glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Human erythroleukemia (HEL) cells synthesize both GPIIb and GPIIIa. Using poly(A+) RNA purified from HEL cells, we constructed a cDNA library in the lambda gt10 phage vector. This library was screened with a 38mer oligonucleotide derived from a platelet GPIIIa peptide, and three overlapping cDNAs were isolated. The three inserts encompassed 3.5 kilobases (kb), including the entire coding region of mature GPIIIa (2,286 basepairs, bp) and 1.3 kb of 3' untranslated sequence. All 222 residues determined directly from platelet GPIIIa tryptic peptides exactly matched the HEL cell-deduced amino acid sequence. The HEL cell sequence matched a previously reported endothelial cell cDNA sequence except for eight nucleotides. Five of these nucleotide differences were silent changes consistent with genetic polymorphisms. The other three differences resulted in changes in the deduced amino acid sequence of GPIIIa; reexamination of the endothelial cell cDNA sequence in these three areas revealed that it is actually identical to the HEL cell sequence. The virtual identity of the endothelial and HEL cell cDNA sequences provides direct evidence that GPIIIa is a subunit common to cell-adhesion receptors present in more than one cell type. We localized the gene for GPIIIa to chromosome 17, the same chromosome to which we had previously mapped the gene for GPIIb.
|
| 3166375 |
Studies on the autophosphorylation of the insulin receptor from human placenta. Analysis of the sites phosphorylated by two-dimensional peptide mapping. |
10.1042/bj2520607 |
Biochem. J. |
Studies on the autophosphorylation of the insulin receptor from human placenta. Analysis of the sites phosphorylated by two-dimensional peptide mapping.
Abstract
- 1. A partially purified preparation of human placental insulin receptors was incubated with [gamma-32P]ATP in the presence or absence of insulin. The 32P-labelled insulin-receptor beta-subunits were then isolated, cleaved with trypsin followed by protease V8 and the [32P]phosphopeptides generated were analysed by thin layer electrophoresis and chromatography. This approach revealed that insulin stimulates autophosphorylation of the insulin-receptor beta-subunit in vitro on at least seven tyrosine residues distributed among three distinct domains. 2. One domain (domain 2), containing tyrosine residues 1146, 1150 and 1151 was the most rapidly phosphorylated and could be recovered as mono-, di- and triphosphorylated peptides cleaved by trypsin at Arg-1143 and either Lys-1153 or Lys-1156. Multiple phosphorylation of this domain appears to partially inhibit the cleavage at Lys-1153 by trypsin. 3. In a second domain (domain 3) containing two phosphorylated tyrosine residues at positions 1316 and 1322 the tyrosines were phosphorylated more slowly than those in domain 2. This domain is close to the C-terminus of the beta-subunit polypeptide chain. 4. At least two further tyrosine residues appeared to be phosphorylated after those in domains 2 and 3. These residues probably residue within a domain lying in close proximity to the inner face of the plasma membrane containing tyrosines 953, 960 and 972, but conclusive evidence is still required. 5. The two-dimensional thin-layer analysis employed in this study to investigate insulin-receptor phosphorylation has several advantages over previous
Methods based on reverse-phase chromatography. It allows greater resolution of 32P-labelled tryptic peptides and, when coupled to radioautography, is considerably more sensitive. The approach can be readily adapted to study phosphorylation of the insulin receptor within intact cells.
|
| 3182836 |
Purification of three antibacterial proteins from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina |
None |
J Biol Chem |
Purification of three antibacterial proteins from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina
Abstract
- Three antibacterial proteins were purified from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina (flesh fly). Sequencing studies showed that two of these proteins belong to the sarcotoxin I family, potent antibacterial proteins purified from the hemolymph of Sarcophaga larvae, whereas the other protein, named sapecin, is a new protein consisting of 40 amino acid residues including 6 cysteine residues. Unlike sarcotoxin I, sapecin preferentially represses the growth of various Gram-positive bacteria. The proteins of the sarcotoxin I family produced by this cell line were found to have carboxyl-terminal glycine, whereas sarcotoxin I in the hemolymph has amidated amino acids. This suggests that the embryonic cells lack an enzyme that cleaves off carboxyl-terminal glycine to form a new amidated carboxyl terminus.
|
| 3188055 |
Strongly enhanced toxicity of the mushroom toxin alpha-amanitin by an amatoxin-specific Fab or monoclonal antibody |
10.1016/0041-0101(88)90188-2. |
Toxicon |
Strongly enhanced toxicity of the mushroom toxin alpha-amanitin by an amatoxin-specific Fab or monoclonal antibody
Abstract
- A monoclonal antibody, with high affinity against the mushroom toxin alpha-amanitin, was prepared. Administration of the Fab fragment of the monoclonal antibody to mice caused a 50-fold increase in alpha-amanitin toxicity. Electron micrographs showed normal appearance of hepatocytes but typical, amanitin-induced lesions in cells of the proximal convoluted tubules of the kidney. The pronounced nephrotoxicity is mainly explained by glomerular filtration and tubular reabsorption of the Fab-amatoxin complex and, to a lesser extent, of the immunoglobulin-amatoxin complex, which is still c. Twice as toxic as free alpha-amanitin. To our knowledge this is the first reported case where immunoglobulins or their fragments enhance rather than decrease the activity of a toxin. Accordingly, immunotherapy of Amanita mushroom poisoning in humans does not appear promising.
|
| 3190203 |
New class of antifungal agents: jasplakinolide, a cyclodepsipeptide from the marine sponge, Jaspis species |
10.1128/AAC.32.8.1154. |
Antimicrob Agents Chemother |
New class of antifungal agents: jasplakinolide, a cyclodepsipeptide from the marine sponge, Jaspis species
Abstract
- Jasplakinolide is a cyclodepsipeptide which represents a new class of antifungal agents with potent activity against Candida albicans. Jasplakinolide is fungicidal against C. albicans with both a MIC and a minimum lethal concentration of 25 micrograms/ml in a broth dilution assay. This activity compares to that of the imidazole miconazole nitrate, which had a MIC of 6.2 micrograms/ml and a minimum lethal concentration of 50 micrograms/ml in the same assay. Topical administration of 2% jasplakinolide cream against a murine vaginal C. albicans infection was equivalent in efficacy to administration of miconazole nitrate at 2%. Subcutaneous administration of jasplakinolide was not effective against a systemic murine C. albicans infection.
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