| 7647302 |
Cloning and characterization of two cDNA clones encoding seed-specific antimicrobial peptides from Mirabilis jalapa L |
10.1007/BF00021195. |
Plant Mol Biol |
Cloning and characterization of two cDNA clones encoding seed-specific antimicrobial peptides from Mirabilis jalapa L
Abstract
- We have isolated and characterized two cDNA clones (designated MJ1 and MJ2) encoding the two Mirabilis jalapa antimicrobial peptides (Mj-AMP1 and Mj-AMP2, respectively), which were previously purified from seeds of this plant species (Cammue et al. (1992), J Biol Chem 267: 2228-2233). In both cases, the deduced amino acid sequences reveal the presence of a putative signal sequence preceding the mature peptide, indicating that the Mj-AMPs are expressed as preproteins. The Mj-AMP1- and Mj-AMP2-encoding genes are interrupted in their coding sequences by a single intron (380 bp and 900 bp for Mj-AMP1 and Mj-AMP2 genes, respectively). Southern blot analysis indicates that the Mj-AMP-encoding genes belong to a gene family of low complexity. Northern blot analysis suggests seed-specific expression of Mj-AMPs since transcripts of the expected size could only be detected in near-mature and in mature seeds of M. jalapa.
|
| 7649185 |
Characterization and gene cloning of 1,3-beta-D-glucan synthase from Saccharomyces cerevisiae. |
10.1111/j.1432-1033.1995.tb20770.x |
Eur. J. Biochem. |
Characterization and gene cloning of 1,3-beta-D-glucan synthase from Saccharomyces cerevisiae.
Abstract
- 1,3-beta-D-Glucan synthase of Saccharomyces cerevisiae was solubilized and purified up to 700-fold by product entrapment. The specific activity of the partially purified enzyme was around 4 mumol glucose incorporated.min-1.mg protein-1. In SDS/PAGE, enrichment of a 200-kDa protein was clearly observed in parallel with the increase in specific activity. mAbs that could immunoprecipitate the 1,3-beta-D-glucan synthase activity were isolated, and some of them also recognized this 200-kDa protein in the Western blot. Internal amino acid sequences of this 200-kDa protein were determined after lysyl endopeptidase digestion. With the information of these amino acid sequences, we cloned two genes, GSC1 and GSC2 (glucan synthase of S. cerevisiae 1 and 2), which are very similar to each other (88% at the amino acid level); hydropathy profiles of both proteins suggest that these genes encode integral membrane proteins which can be assumed to have approximately 16 transmembrane domains. Disruption of each gene was not lethal, but disruption of both genes was lethal. The 1,3-beta-D-glucan synthase activities of membrane and partially purified enzyme of gsc1::URA3 cells were significantly lower than those of the wild-type and gsc2::LEU2 cells.
|
| 7650681 |
Semisynthetic chemical modification of the antifungal lipopeptide echinocandin B (ECB): structure-activity studies of the lipophilic and geometric parameters of polyarylated acyl analogs of ECB |
10.1021/jm00017a012. |
J Med Chem |
Semisynthetic chemical modification of the antifungal lipopeptide echinocandin B (ECB): structure-activity studies of the lipophilic and geometric parameters of polyarylated acyl analogs of ECB
Abstract
- Echinocandin B (ECB) is a lipopeptide composed of a complex cyclic peptide acylated at the N-terminus by linoleic acid. Enzymatic deacylation of ECB provided the peptide "nucleus" as a biologically inactive substrate from which novel ECB analogs were generated by chemical reacylation at the N-terminus. Varying the acyl group revealed that the structure and physical properties of the side chain, particularly its geometry and lipophilicity, played a pivotal role in determining the antifungal potency properties of the analog. Using CLOGP values to describe and compare the lipophilicities of the side chain fragments, it was shown that values of > 3.5 were required for expression of antifungal activity. Secondly, a linearly rigid geometry of the side chain was the most effective shape in enhancing the antifungal potency. Using these parameters as a guide, a variety of novel ECB analogs were synthesized which included arylacyl groups that incorporated biphenyl, terphenyl, tetraphenyl, and arylethynyl groups. Generally the glucan synthase inhibition by these analogs correlated well with in vitro and in vivo activities and was likewise influenced by the structure of the side chain. These structural variations resulted in enhancement of antifungal activity in both in vitro and in vivo assays. Some of these analogs, including LY303366 (14a), were effective by the oral route of administration.
|
| 7651325 |
In vivo reconstitution of an active siderophore transport system by a binding protein derivative lacking a signal sequence. |
10.1007/bf02456611 |
Mol. Gen. Genet. |
In vivo reconstitution of an active siderophore transport system by a binding protein derivative lacking a signal sequence.
Abstract
- Transport of iron (III) hydroxamates across the inner membrane of Escherichia coli depends on a binding protein-dependent transport system composed of the FhuB, C and D proteins. The FhuD protein, which is synthesized as a precursor and exported through the cytoplasmic membrane, represents the periplasmic binding protein of the system, accepting as substrates a number of hydroxamate siderophores and the antibiotic albomycin. A FhuD derivative, carrying an N-terminal His-tag sequence instead of its signal sequence and therefore not exported through the inner membrane, was purified from the cytoplasm. Functional activity, comparable to that of wild-type FhuD, was demonstrated for this His-tag-FhuD in vitro by protease protection experiments in the presence of different substrates, and in vivo by reconstitution of iron transport in a fhuD mutant strain. The experimental data demonstrate that the primary sequence of the portion corresponding to the mature FhuD contains all the information required for proper folding of the polypeptide chain into a functional solute-binding protein. Moreover, purification of modified periplasmic proteins from the cytosol may be a useful approach for recovery of many polypeptides which are normally exported across the inner membrane and can cause toxicity problems when overproduced.
|
| 7654368 |
Possible role of variant RNA transcripts in the regulation of epidermal growth factor receptor expression in human placenta. |
10.1002/mrd.1080410205 |
Mol. Reprod. Dev. |
Possible role of variant RNA transcripts in the regulation of epidermal growth factor receptor expression in human placenta.
Abstract
- Epidermal growth factor receptor (EGFR) plays an important role in growth and differentiation. The human placenta expresses high levels of the receptor. In the placenta, as in many other human tissues, EGFR is encoded by two RNA transcripts of 5.8 kb and 10.5 kb. The placenta also expresses a putative truncated EGFR transcript of 1.8 kb, which encodes only the ligand binding domain of the receptor. The etiology and role of these variant EGFR transcripts is unknown. Using the human placenta as a model to study this area, we report 1) the relationships among these transcripts suggest that the induction of alternate pathways of EGFR RNA processing is involved in their etiologies; 2) the 10.5 kb transcript may be the principal transcript involved in determining the level of the protein receptor; and 3) the isolation of a soluble protein with characteristics consistent with a translational product corresponding to the 1.8 kb transcript, which may act in regulating the activity of EGFR. Together these
Results suggest that alternate processing of EGFR RNA into variant transcripts may represent a novel mechanism involved in the regulation of the receptor protein.
|
| 7657032 |
Frequency of mutations of insulin receptor gene in Japanese patients with NIDDM |
10.2337/diab.44.9.1081. |
Diabetes |
Frequency of mutations of insulin receptor gene in Japanese patients with NIDDM
Abstract
- To examine the prevalence of abnormalities in the insulin receptor structure gene in Japanese with non-insulin-dependent diabetes mellitus (NIDDM), a population of 51 patients with NIDDM was screened for mutations in this gene. Patient genomic DNAs of both alleles corresponding to 22 exons of the gene were amplified by polymerase chain reaction (PCR). The PCR products on pUC19 were sequenced. Three patients with heterozygous missense mutation Thr831-->Ala831 in exon 13 and one patient with heterozygous missense mutation Tyr1334-->Cys1334 in exon 22 of the beta-subunits were identified. Linkage analysis of one of the families plus statistical studies showed that the mutation Thr831-->Ala831 is possibly responsible for the onset of NIDDM. In COS cells transiently expressing both mutant receptor cDNAs and a cDNA of a M(r) 85,000 regulatory subunit of phosphatidylinositol 3-kinase (PI 3-kinase), the mutation Tyr1334-->Cys1334 impaired binding of the receptor with the M(r) 85,000 subunit of PI 3-kinase, but linkage analysis of the family showed that the mutation did not cosegregate with NIDDM in the pedigree. Therefore, one missense mutation (Thr831-->Ala831) in the insulin receptor, as found in three patients, is possibly involved in the etiology of a subset of the 51 NIDDM patients.
|
| 7657591 |
Tyrosine phosphorylation of the c-cbl proto-oncogene protein product and association with epidermal growth factor (EGF) receptor upon EGF stimulation |
10.1074/jbc.270.35.20242. |
J Biol Chem |
Tyrosine phosphorylation of the c-cbl proto-oncogene protein product and association with epidermal growth factor (EGF) receptor upon EGF stimulation
Abstract
- The murine retroviral oncogene v-cbl induces pre-B cell lymphomas and myelogenous leukemias. The protein product of the mammalian c-cbl proto-oncogene is a widely expressed cytoplasmic 120-kDa protein (p120cbl) whose normal cellular function has not been determined. Here we show that upon stimulation of human epidermal growth factor (EGF) receptor, p12ocbl becomes strongly tyrosine-phosphorylated and associates with activated EGF receptor in vivo. A GST fusion protein containing amino acids 1-486 of p120cbl, including a region highly conserved in nematodes, binds directly to the autophosphorylated carboxyl-terminal tail of the EGF receptor. Platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), or nerve growth factor (NGF) stimulation also results in tyrosine phosphorylation of p120cbl. Recent genetic studies in Caenorhabditis elegans indicate that Sli-1, a p120cbl homologue, plays a negative regulatory role in control of the Ras signaling pathway initiated by the C. elegans EGF receptor homologue. Our results indicate that p120cbl is involved in an early step in the EGF signaling pathway that is conserved from nematodes to mammals.
|
| 7664271 |
Association of the DF3/MUC1 breast cancer antigen with Grb2 and the Sos/Ras exchange protein |
None |
Cancer Res |
Association of the DF3/MUC1 breast cancer antigen with Grb2 and the Sos/Ras exchange protein
Abstract
- The DF3/MUC1 mucin-like glycoprotein is aberrantly overexpressed in human breast carcinomas. Although the precise functional role of this protein remains unclear, the cytoplasmic tail contains potential tyrosine phosphorylation sites for binding to Src homology 2 (SH2) domains. In the present studies using human MCF-7 breast cancer cells, we show that tyrosine phosphorylated DF3 directly interacts with the SH2 domain of the adaptor protein Grb2. The findings indicate that a pYTNP site in DF3 is responsible for this interaction. The results also demonstrate that the DF3/Grb2 complex associates with the guanine nucleotide exchange protein Sos. Because Sos binds to the SH3 domains of Grb2 and, thereby, associates with Ras at the cell membrane, formation of a DF3/Grb2/Sos complex supports a role for DF3 in intracellular signaling.
|
| 7673942 |
Cyclic peptides from higher plants, Part 15. Pseudostellarin H, a new cyclic octapeptide from Pseudostellaria heterophylla |
10.1021/np50120a021. |
J Nat Prod |
Cyclic peptides from higher plants, Part 15. Pseudostellarin H, a new cyclic octapeptide from Pseudostellaria heterophylla
Abstract
- A new cyclic octapeptide, pseudostellarin H 1, was isolated from the roots of Pseudostellaria heterophylla. Based on spectral evidence and chemical degradation, the primary structure of 1 was established as cyclo(Gly-Thr-Pro-Thr-Pro-Leu-Phe-Phe).
|
| 7673945 |
Antineoplastic agents, 325. Isolation and structure of the human cancer cell growth inhibitory cyclic octapeptides phakellistatin 10 and 11 from Phakellia sp |
10.1021/np50120a025. |
J Nat Prod |
Antineoplastic agents, 325. Isolation and structure of the human cancer cell growth inhibitory cyclic octapeptides phakellistatin 10 and 11 from Phakellia sp
Abstract
- The two new marine sponge (Phakellia sp., western Pacific Ocean) constituents, phakellistatin 10 1 and 11 2, were found to be cyclic octapeptides that significantly inhibited growth of the murine P-388 lymphocytic leukemia (ED50 values of 2.1 and 0.20 micrograms/ml, respectively) and human cancer cell lines. The structures were established based on results of extensive tandem ms/ms and high-field (500-MHz) 2D 1H- and 13C-nmr analyses. All of the amino acid units (except Trp, not determined) were found to correspond to the (S)-configuration.
|
| 7679099 |
Role of tyrosine kinase activity in signal transduction by the insulin- like growth factor-I (IGF-I) receptor. Characterization of kinase-deficient IGF-I receptors and the action of an IGF-I-mimetic antibody (alpha IR-3). |
10.1016/s0021-9258(18)53824-2 |
J. Biol. Chem. |
Role of tyrosine kinase activity in signal transduction by the insulin- like growth factor-I (IGF-I) receptor. Characterization of kinase-deficient IGF-I receptors and the action of an IGF-I-mimetic antibody (alpha IR-3).
Abstract
- The insulin-like growth factor-I (IGF-I) receptor is a member of a large family of transmembrane signal transducing molecules. The defining characteristic of this class of receptors is the intrinsic tyrosine kinase activity of the cytoplasmic domain. While it has been demonstrated that this tyrosine kinase activity is necessary for the action of a number of transmembrane tyrosine kinase receptors, no evidence of this type has been adduced to date with respect to the signaling requirement of the IGF-I receptor. We have now shown that stably transfected NIH-3T3 cell lines overexpressing human IGF-I receptors display increased responses to IGF-I and an IGF-I-mimetic antibody, alpha IR-3, in terms of short, intermediate, and long term actions initiated by activation of the IGF-I receptor. These include receptor autophosphorylation, activation of phosphatidylinositol-3-kinase and 2-deoxyglucose uptake, induction of ornithine decarboxylase gene expression, and stimulation of thymidine incorporation. In short term responses, the kinetics seen with alpha IR-3 were slower than those seen with IGF-I. These effects were severely decreased in clones expressing human IGF-I receptors in which the lysine residue in the ATP-binding site of the tyrosine kinase domain had been mutated to alanine or arginine. This was true for both IGF-I and alpha IR-3. These
Results indicate that, for all parameters tested, the tyrosine kinase activity of the IGF-I receptor is necessary for activation of the IGF-I-stimulated signal transduction cascade. Additionally, the effects of alpha IR-3 also require tyrosine kinase activity.
|
| 7679104 |
Amphiregulin induces tyrosine phosphorylation of the epidermal growth factor receptor and p185erbB2. Evidence that amphiregulin acts exclusively through the epidermal growth factor receptor at the surface of human epithelial cells |
None |
J Biol Chem |
Amphiregulin induces tyrosine phosphorylation of the epidermal growth factor receptor and p185erbB2. Evidence that amphiregulin acts exclusively through the epidermal growth factor receptor at the surface of human epithelial cells
Abstract
- The COOH-terminal half of the amphiregulin (AR) molecule has sequence homology to epidermal growth factor (EGF). The ability of AR to elicit in vivo phosphorylation of the EGF receptor (EGFR) and p185erbB2 was studied in four human epithelial cell lines which expressed either or both of the receptor tyrosine kinases. AR induced the phosphorylation of the EGFR and p185erbB2, and phosphoamino acid analysis revealed enhanced phosphorylation of tyrosine residues in both receptor proteins. A monoclonal antibody (mAb) which binds to the extracellular domain of the EGFR blocked the phosphorylation of the EGFR and p185erbB2 as well as AR-induced mitogenesis indicating that the EGFR mediated these responses. In MDA-MB-453 cells which lack EGFRs, AR did not induce phosphorylation of p185erbB2, did not affect proliferation, and had no detectable effect on the phosphorylation of cellular proteins isolated using an anti-phosphotyrosine mAb. Qualitatively, in vivo phosphorylations induced by AR and EGF were found to be indistinguishable as demonstrated by analysis of cellular 32P-labeled proteins isolated with the anti-phosphotyrosine mAb. Moreover, in the presence of the anti-EGFR mAb, AR had no effect on the proliferation of cells. These results provide strong evidence that the EGFR is the sole cell surface mediator of the action of AR in human epithelial cells.
|
| 7680185 |
Modulation of vitronectin receptor-mediated osteoclast adhesion by Arg-Gly-Asp peptide analogs: a structure-function analysis |
10.1002/jbmr.5650080215. |
J Bone Miner Res |
Modulation of vitronectin receptor-mediated osteoclast adhesion by Arg-Gly-Asp peptide analogs: a structure-function analysis
Abstract
- This study details the investigation of induction of retractile shape change in the osteoclast through inhibition of adhesion between osteoclasts and matrix with (1) peptide analogs bearing an Arg-Gly-Asp (RGD) sequence, (2) antibodies to the integrin alpha V beta 3 vitronectin receptor, and (3) the RGD-containing snake venom peptide echistatin. Osteoclast retraction on dentin has been demonstrated for GRGDSP peptide, in contrast to the inactivity of the analog containing the conservative RGE sequence modification. An osteoclast adhesion assay employing rat or chick bone cells and serum-coated glass coverslips as substrate was developed for routine evaluation of inhibition of adhesion. Antibodies F4 and F11 to the beta 3 chain of rat vitronectin receptor were effective at submicromolar concentrations in rat osteoclasts (IC50 0.29 and 0.05 microM, respectively), whereas MAb 23C6 to human/chick vitronectin receptor was somewhat less effective against chick osteoclasts (IC50 1.6 microM). A rank order of RGD analog activity (mean IC50, microM) in the serum-coated glass adhesion assay was derived for the linear peptides GRGDSP (201 microM), GRGDTP (180 microM), Ac-RGDS-NH2 (84 microM), Ac-RGDV-NH2 (68 microM), RGDV (43 microM), GRGDS (38 microM), and RGDS (26 microM). The two most potent short peptides were the cyclic analog SK&F 106760 Ac-S,S-cyclo-(Cys-(N alpha Me)Arg-Gly-Asp-Pen)-NH2 (IC50 7.0 microM), and the Telios peptide H-Gly-S,S-cyclo-(Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys)-Ala-OH (IC50 6.6 microM). The snake venom peptide echistatin was the most potent substance evaluated in the serum-coated glass assay (IC50 0.78 nM) employing either rat or chick osteoclasts.(ABSTRACT TRUNCATED AT 250 WORDS)
|
| 7689274 |
New immunosuppressive drugs in transplantation |
None |
Transplant Proc |
New immunosuppressive drugs in transplantation
Abstract
|
| 7693310 |
Effects of two diketopiperazines, cyclo (His-Pro) and cyclo (Asp-Phe), on striatal dopamine: a microdialysis study |
10.1016/0361-9230(93)90171-7. |
Brain Res Bull |
Effects of two diketopiperazines, cyclo (His-Pro) and cyclo (Asp-Phe), on striatal dopamine: a microdialysis study
Abstract
- The effects of two diketopiperazines, Cyclo (His-Pro) (CHP) and Cyclo (Asp-Phe) (CAP), on striatal extracellular levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) were examined using in vivo microdialysis in anaesthetized rats. Treatment with neither CHP (0.1-10 mg/kg IP and 0.3 mg/kg i.v.) nor CAP (0.1-10 mg/kg IP and 10 mg/kg PO) significantly changed the efflux of DA, DOPAC, HVA, or 5-HIAA when compared to the effects of treatment with saline. Our results suggest that systemic administration of CHP or CAP alone does not modify striatal dopaminergic neurotransmission. The previous findings of enhanced DA release by systemic administration of thyrotropin releasing hormone (TRH) are probably not explained by formation of CHP from TRH.
|
