Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The backbone dynamics of the uniformly 15N-labeled ribonuclease H (RNase H) domain of human immunodeficiency virus (HIV-1) reverse transcriptase have been investigated using two-dimensional inverse-detected heteronuclear 15N-1HNMR spectroscopy. 15N T1, T2, and nuclear Overhauser enhancement (NOE) data were obtained for 107 out of a total of 134 backbone amide groups. The overall rotational correlation time (tau R) for the protein at 26 degrees C is 10.4 ns. The backbone N-H vectors for all the measurable residues exhibit very fast motions on a time scale of less than or equal to 20 ps. The 15N relaxation data for only 14 residues can be explained by this single internal motion alone. A further 39 residues display a second motion on a time scale ranging from 28.8 ps to 3.9 ns, while another 15 residues are characterized by an additional motion on the 170-ns to 2.25-ms time scale resulting in 15N T2 exchange line broadening. There are 39 residues that exhibit both the additional 15N T2 exchange line broadening and the slow (28.8 ps-3.9 ns) internal motion. Thus, the RNase H domain experiences extensive mobility throughout its structure as evidenced by the 93 residues which exhibit multiple modes of motion. Distinctly mobile regions of the protein are identified by large decreases in the overall order parameter (S2) and correspond to the C-terminal residues and the loop regions between beta-strands beta 1 and beta 2 and between alpha-helix alpha B and beta-strand beta 4.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Analysis of the backbone dynamics of the ribonuclease H domain of the human immunodeficiency virus reverse transcriptase using 15N relaxation measurements. 138 87

Allelic variation in the DR subregion of the canine major histocompatibility complex (DLA) has been analyzed by nucleic acid sequencing of cDNA clones of DRB genes amplified in vitro by the reverse transcriptase-polymerase chain reaction (RT-PCR). Sequence analysis of a panel of 19 homozygous typing cell dogs representing 12 different DLA-D types (defined by mixed leucocyte reaction) demonstrated the presence of one expressed DRB locus with at least nine distinct alleles in the dog. Unique DLA-DRB alleles were found in the DLA-D types Dw1, Dw3, Dw4, Dw8 (workshop assignments) and D4, D6, D7, D8, and D9 (Seattle assignments). In contrast, the DRB genes of the remaining three DLA-D types (D1, D10, and D16) were identical to those of Dw3/Dw4 (for D1), Dw8 (for D10), and D6 (for D16). The nucleotide sequences of all nine DLA-DRB alleles were typical of functional major histocompatibility complex (MHC) class II beta chains and contained three allelic hypervariable regions (HVRs) in the beta 1 domain at positions 8-16, 26-39, and 57-74. At each variable residue, two to five amino acid substitutions were found. The most polymorphic residues were located at positions 37 (with five amino acid substitutions), 11, 13, 28, and 71 (each with four substitutions). The DLA-DRB alleles had 96%-99% overall nucleotide sequence similarity and 93%-99% amino acid sequence similarity with each other. Cluster analysis of the nucleotide and predicted amino acid sequences subdivided the DLA-DRB alleles into three major allelic groups which may represent the canine counterparts of the supertypic groups described in man.
...
PMID:Allelic variation in the DR subregion of the canine major histocompatibility complex. 237 25

The molecular mechanisms that underlie ethanol dependence appear to involve alterations in GABAA receptor function and gene expression. In rat cerebral cortex, chronic exposure to ethanol alters many functional properties of GABAA receptors, including reduction of GABAA receptor-mediated chloride uptake. These functional alterations occur without a concomitant alteration in total receptor density or affinity. Previous investigations have shown that chronic ethanol exposure elicits alterations in mRNA and polypeptide levels for several abundant GABAA receptor subunits. For example, alpha 1 and alpha 2 subunit mRNA and polypeptide levels have been shown to decrease with chronic ethanol exposure. The present study was undertaken to further investigate the effects of chronic ethanol consumption on GABAA receptor subunit mRNA levels in rat cerebral cortex by using a competitive, quantitative reverse transcriptase-polymerase chain reaction assay that incorporates subunit-specific internal standards and allows for the absolute quantification of mRNA levels. We find that chronic ethanol consumption elicits a significant increase in alpha 4 subunit mRNA levels that is equal, in absolute amount, to a decrease in alpha 1 subunit mRNA levels. There is a small (30%) increase in gamma 2S but not gamma 2L subunit mRNA levels after chronic ethanol consumption. In addition, gamma 1 subunit mRNA levels are increased by 70%, whereas alpha 5, beta 1, beta 2, beta 3, gamma 3, and delta subunit mRNA levels do not change. We also reproduced results obtained previously by Northern blot analysis showing a 40% reduction in alpha 1 mRNA levels with no change in beta 2 subunit mRNA levels after chronic ethanol consumption. These results are consistent with the hypothesis that chronic ethanol consumption alters the function of GABAA receptors by eliciting changes in receptor subunit assembly. These changes may underlie the development of ethanol dependence.
...
PMID:Chronic ethanol consumption differentially alters the expression of gamma-aminobutyric acidA receptor subunit mRNAs in rat cerebral cortex: competitive, quantitative reverse transcriptase-polymerase chain reaction analysis. 747 17

The expression of different myocardial regulatory proteins is altered in human heart failure, e.g., beta 1-adrenoceptors, G-proteins and others. Similar changes in rats after 4 days treatment with isoproterenol led to the hypothesis of the cAMP pathway involved in these changes. In different cell types cAMP-dependent transcriptional activation is mediated by the cAMP-response element binding protein (CREB) which was recently shown to be expressed and phosphorylated in the human heart. Here, by the reverse transcriptase-polymerase chain reaction two alternatively spliced isoforms of CREB mRNA were found to be expressed in rat ventricles. Both isoforms were down-regulated in the ventricles of rats treated in vivo with isoproterenol (2.4 mg/kg per day) for 4 days proposing a possible mechanism involved in expressional changes mentioned above.
...
PMID:In vivo isoproterenol treatment leads to downregulation of the mRNA encoding the cAMP response element binding protein in the rat heart. 748 29

The mRNA's of several integrin subunits are alternatively spliced in the region encoding cytoplasmic domains, that may potentially provide alternative integrin-cytoskeleton interactions and transmembrane signaling pathways. We identified a novel cytoplasmic tail variant of the human beta 1 subunit by reverse transcriptase polymerase chain reaction. This fourth beta 1 variant, named beta 1D, is specific for skeletal and cardiac muscle. The determined genomic organization of the 3'-region of the human beta 1 gene reveals that beta 1D is produced by alternative splicing of mRNA. In addition, we show that the expression of beta 1D is developmentally regulated during murine myoblast differentiation, suggesting a role for beta 1D in myogenesis.
...
PMID:A novel beta 1 integrin isoform produced by alternative splicing: unique expression in cardiac and skeletal muscle. 754 98

Retinal pigment epithelial (RPE) cells produce and respond to a variety of cytokines; however, molecular and biochemical studies are restricted by the limited access to large numbers of pure cells and the variability associated with different donor sources. Despite success in establishing primary human RPE (HRPE) cell cultures, the inability to sustain consistent proliferation rates and morphology over several passages remains a concern. This problem was approached by using an immortalized line of simian virus (SV)40 transformed fetal HRPE cells (SVRPE). Cytokine production, receptor expression and responsiveness in the SVRPE cell line was analyzed to determine the usefulness of this model for studying HRPE-cytokine interactions. Using reverse transcriptase polymerase chain reaction (RT-PCR), HRPE and SVRPE cells demonstrated an identical pattern of interleukin-1 receptor (IL-1R), IL-2R (alpha sub-unit), IL-6R, interferon (IFN)-gamma R and tumor necrosis factor-alpha (TNF)R p55 expression. No amplification products for TNFR p75 or granulocyte/macrophage colony stimulating factor (GM-CSF)R were demonstrated in either population. IFN-gamma stimulation induced surface human leukocyte antigen (HLA)-DR in both SVRPE and HRPE, while TNF treatment induced surface expression of intercellular adhesion molecule (ICAM)-1 on SVRPE and upregulated ICAM from basal levels on HRPE. Both cell types showed amplification products for interleukin (IL)-1 beta, IL-6 and transforming growth factor (TGF)-beta 1 using RT-PCR. The bioassays demonstrated that both populations of unstimulated cells constitutively secrete very low levels of TGF-beta and no IL-6.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:SV40-immortalized and primary cultured human retinal pigment epithelial cells share similar patterns of cytokine-receptor expression and cytokine responsiveness. 754 67

Variants in the extracellular domain of the integrin alpha 7 subunit which arise as a consequence of alternative splicing of mRNA have recently been reported. Two alternative exons, X1 and X2, have been identified in the alpha 7 gene, and homologous exons were found for alpha 6 (Ziober et al., 1993). In this study, we have isolated the region of the alpha 6 gene containing exons X1 and X2 that are, like those of alpha 7, located between stretches of DNA that encode the homologous repeat domains III and IV, proximal to the three divalent cation binding sites of the alpha 6 subunit. We demonstrated by reverse transcriptase polymerase chain reactions and confirmed by sequencing that alpha 6X1 and alpha 6X1X2 mRNAs are generated by alternative splicing of exon X2. The alpha 6X1X2 mRNA is expressed in a limited number of tissues and cell lines and it is always co-expressed with the ubiquitous alpha 6X1 mRNA. Stable transfection of K562 cells with full length cDNAs for the alpha 6AX1X2 and beta 4 subunits resulted in cell populations that expressed the alpha 6AX1X2 variant, in association with either beta 1 or beta 4, on their surface. In addition, a population of cells was isolated that expressed the alpha 6AX1X2 variant at low levels and almost exclusively in association with beta 1. Comparison of the alpha 6AX1X2 integrins with alpha 6AX1 using similarly transfected cells showed no obvious differences between the alternative extracellular alpha 6A isoforms with respect to ligand specificity and activation-dependency of ligand binding. After treatment with the anti-beta 1 stimulatory antibody TS2/16, both the alpha 6AX1 beta 1 and alpha 6AX1X2 beta 1 integrin variants mediated cell adhesion to EHS tumor laminin (laminin-1), kalinin (laminin-5), human placental (laminin-2 and -4) and bovine kidney laminins. In contrast, the alpha 6AX1 beta 4 and alpha 6AX1X2 beta 4 integrins also mediated cell adhesion to laminin and kalinin without stimulation. Furthermore, the different transfectants did not differ in their ability to spread on kalinin. The presented data indicate that the X2 region in alpha 6 is not involved in defining ligand specificity or affinity.
...
PMID:An alternatively spliced exon in the extracellular domain of the human alpha 6 integrin subunit--functional analysis of the alpha 6 integrin variants. 758 7

Integrins alpha 1 beta 1 and alpha 2 beta 1 are major cellular receptors for collagens. The alpha 1 and alpha 2 subunits contain a approximately 200 amino acid inserted domain (I-domain) in their N-terminal region and, because of the homology between the I-domains and the collagen-binding A-domains of von Willebrand factor, it has been suggested that the I-domains might mediate the collagen-binding functions of alpha 1 beta 1 and alpha 2 beta 1. In order to fully investigate this hypothesis, we have generated recombinant human alpha 2 I-domain (r alpha 2I) by reverse transcriptase-polymerase chain reaction/bacterial expression and tested its ability to mediate the collagen-binding functions of alpha 2 beta 1. R alpha 2 I binds specifically to type I collagen in a concentration-dependent manner: binding is cation dependent and, like the complete receptor, is supported by magnesium and manganese ions but not by calcium ions. R alpha 2I is recognised by anti-functional anti-alpha 2 monoclonal antibodies 6F1, 5E8 and P1E6 in capture ELISAs, and anti-functional antibodies inhibited r alpha 2I-collagen binding. In addition, r alpha 2I inhibits cell spreading on collagen. R alpha 2I is therefore a collagen-binding domain and can account for many of the collagen-binding functions of integrin alpha 2 beta 1. We have also determined the collagen specificity of r alpha 2I and found that it binds types I, II and XI collagen.
...
PMID:Integrin alpha 2 I-domain is a binding site for collagens. 761 81

We studied the effects of thyroid hormone (T3) on GH, TSH, and T3 receptor (TR) gene expression as well as deiodinase activities during rat pituitary development. By reverse transcriptase-polymerase chain reaction, GH and TSH beta transcripts were detectable on fetal day 15. Although with certain differences, the expression of both GH and TSH beta genes was under T3 control during fetal and neonatal life. Differences in plasma, but not pituitary, TSH concentrations were observed between control and hypothyroid animals throughout the period studied. Both TR alpha and TR beta genes were expressed in the fetal pituitary. TR alpha 1, TR beta 2, and c-erbA alpha 2 transcripts displayed a developmental profile different from that of TR beta 1. Thyroid hormone repressed TR alpha 1, TR beta 2, and c-erbA alpha 2 and stimulated TR beta 1. Type I and type II deiodinase activities (5'DI and 5'DII, respectively) had different ontogenic patterns; 5'D-II was the predominant activity in fetuses, with levels similar to those in adults, whereas the level of 5'D-I was low and increased with age. T3 stimulated 5'D-I and decreases 5'D-II. These results demonstrate that in somatotroph and thyrotroph cells, the mechanisms responsible for T3 action are mature and active very early in development and suggest an involvement of this hormone in the establishment and/or maintenance of the somatotroph and thyrotroph phenotype.
...
PMID:Effect of perinatal hypothyroidism on the developmental regulation of rat pituitary growth hormone and thyrotropin genes. 766 53

A beta 1 subunit associated with one or more isoforms of brain voltage-sensitive Na channels has previously been cloned, sequenced and expressed. Northern and Western blot analyses have suggested that homologues to this protein are expressed in skeletal muscle and heart. Here, reverse transcriptase-polymerase chain reaction (RT-PCR)/cloning reveals that transcripts encoding identical beta 1 subunit ORFs are expressed in adult rat brain, skeletal muscle and heart. Heterologous co-expression of beta 1 with brain (RIIA) and skeletal muscle (mu 1) alpha subunits caused a stabilization of normal, rapidly inactivating (mode 1) gating relative to anomalous, non-inactivating (mode 2) states and a negative shift in steady state inactivation. Chromosome mapping of the beta 1 subunit showed a single locus (Scn1b) in mouse chromosome 7 1.8 cM (+/- 1.2 cM) distal to D19F11S1h and 0.9 cM (+/- 0.9 cM) proximal to Pkca. This locus is in the region of the mouse mutant "quivering," characterized by a variety of neurological disorders and muscle paralysis. A mutation in a single beta 1 subunit forming functional complexes with multiple Na channel isoforms could underlie these deficits.
...
PMID:A single B1 subunit mapped to mouse chromosome 7 may be a common component of Na channel isoforms from brain, skeletal muscle and heart. 769 May 58


1 2 3 4 5 6 Next >>

---