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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthesis of RNA polymerase subunits and of transcription termination factor p was studied after thermoinduction of prophage lambdac1857 located at several unusual sites on the chromosome of Escherichia coli. When a lysogen carrying the prophage at the bfe gene was induced at 42 degrees C, the rate of synthesis of core polymerase subunits (alpha, beta and beta') rapidly decreased, followed by a marked increase after about 10 min. The latter increase was observed specifically in the "bfe lysogen" and not in any of the other lysogens tested. Similarly, the rate of synthesis of p factor increased appreciably in the induced ilv lysogen carrying the prophage at the ilv gene, and possibly in the bfe lysogen as well, but not in other lysogens examined. Taken together with other evidence, these results suggest that the enhanced syntheses of beta and beta' subunits of RNA polymerase and of p factor observerd represent "escape synthesis", resulting from the close linkage of the prophage genome to the respective structural genes. In contrast, omega factor synthesis was stimulated upon induction of any of the lysogens used without respect to the site of prophage location, suggesting the involvement of an entirely different mechanism.
Mol Gen Genet 1977 Feb 15
PMID:Escape synthesis of RNA polymerase subunits and termination factor rho following induction of prophage lambda in Escherichia coli. 32 39

As an effort to elucidate the control of quality and quantity of the DNA-dependent RNA polymerase in Escherichia coli, the rate of synthesis of the individual subunits was determined during shift-up and -down of nutrients. When the strain B/r grown in a succinate medium was imposed to a shift-up by adding a mixture of glucose and amino acids, rapid rise was observed of the differential rates of the synthesis of alpha, beta and beta' subunits, the constituents of core enzyme, leading to the increase of core polymerase concentration. The differential rates decreased thereafter to the level characteristic of the post-shift rate of cell growth. Compared to the strain B/r, the adaptation was slow in the strain K12 W3350. On the other hand, upon transfer of the strain B/r from a glucose-amino acids medium to a glucose medium lacking amino acids, the differential rate of core polymerase synthesis decreased rapidly and then regained the rate characteristic of the new growth rate. Similar control was also observed on the rate of ribosomal protein synthesis suggesting the coordinate expression of genes for the core polymerase subunits and ribosomal proteins. Thus, the intracellular concentration of RNA polymerase as well as of ribosomes might be one of the most important factors that affect the rate of bacterial growth. The rate of alpha subunit synthesis, however, exhibited little change during the shift-up but a considerable decrease was observed during the shift-down.
Mol Gen Genet 1975 Dec 23
PMID:Biosynthesis of RNA polymerase in Escherichia coli. II. control of RNA polymerase synthesis during nutritional shift up and down. 76 37

Upon release of rifampicin inhibition of Escherichia coli cells, the initiation of transcription will resume. The sequential resumption of the synthesis of proteins after release of rifampicin inhibition reflects the genetic order and size of the corresponding transcriptional units. We have used this approach to analyze whether the genes for alpha and sigma are on the same transcriptional unit as the genes for beta and beta', employing a method, which allowed us to measure the amounts of RNA polymerase subunits, alpha, beta, beta' and sigma in crude extracts. We have found that the alpha and sigma subunits are synthesized concurrently with the beta subunit in the rifampicin restart experiment, which suggests that the genes for alpha and sigma belongs to different transcriptional units.
Mol Gen Genet 1976 Feb 02
PMID:Biosynthesis of Escherichia coli RNA polymerase subunits upon release of rifampicin inhibition. 76 61

The presence of retinoic acid receptor (RAR) alpha, beta and gamma mRNA was examined in 16 different kinds of rat tissue using the highly sensitive reverse transcriptase-polymerase chain reaction technique. The data demonstrated that each tissue expressed at least two types of RAR mRNA. Among the three types of RAR mRNA, RAR alpha was widely expressed in all types of organ and was the dominant form expressed in the gastrointestinal tract. RAR beta mRNA was not present in the intestine and spleen. In addition, RAR beta mRNA levels were high in the heart, lung, brain, testis and epididymis. RAR gamma mRNA was abundant in both male and female reproductive systems, as well as epidermal tissues. The prevalence of each RAR mRNA in the tissues suggests the diverse biological roles of these receptors.
J Mol Endocrinol 1992 Dec
PMID:Detection of retinoic acid receptor mRNA in rat tissues by reverse transcriptase-polymerase chain reaction. 128 20

The carbocyclic analog of 2'-deoxyguanosine (CdG) is active against herpes simplex virus (HSV), human cytomegalovirus, and human hepatitis-B virus. In order to understand the mechanism of action of this compound against HSV, we have evaluated (a) the incorporation of [3H]CdG into viral and host DNA in HEp-2 cells infected with HSV and (b) the interaction of the 5'-triphosphate of CdG (CdG-TP) with the HSV DNA polymerase and human DNA polymerases alpha, beta, and gamma (EC 2.7.7.7). Incubation of HSV-1-infected HEp-2 cells with [3H]CdG resulted in the incorporation of CdG into both the HSV and the host cell DNA. These results indicated that CdG-TP was used as a substrate for HSV DNA polymerase and for at least one of the cellular DNA polymerases. Degradation of both viral and host DNA with micrococcal nuclease and spleen phosphodiesterase indicated that CdG was incorporated primarily into internal positions in both DNAs. The viral DNA containing CdG sedimented in neutral and alkaline sucrose gradients in the same way as did viral DNA labeled with [3H]thymidine, indicating that the HSV DNA containing CdG was similar in size to untreated HSV DNA. CdG-TP was a competitive inhibitor of the incorporation of dGTP into DNA by the HSV DNA polymerase (Ki of 0.35 microM) and the human DNA polymerase alpha (Ki of 1 microM). CdG-TP was not a potent inhibitor of either DNA polymerase beta or gamma. Using DNA-sequencing technology, CdG-TP was found to be an efficient substrate for HSV DNA polymerase. Incorporation of CdG monophosphate (CdG-MP) into the DNA by HSV DNA polymerase did not interfere with subsequent chain extension. These results suggested that the antiviral activity of CdG was due to its incorporation into the DNA and subsequent disruption of viral functions. In contrast, CdG-TP was not as good as dGTP as a substrate for DNA synthesis by DNA polymerase alpha, and incorporation of CdG-MP by DNA polymerase alpha inhibited further DNA chain elongation.
Mol Pharmacol 1992 Feb
PMID:Incorporation of the carbocyclic analog of 2'-deoxyguanosine into the DNA of herpes simplex virus and of HEp-2 cells infected with herpes simplex virus. 131 7

The GABAA receptor belongs to the ligand-gated ion channel receptor superfamily and appears to be composed of from 4 to 5 subunits which interact with each other. Molecular cloning of cDNAs encoding the different subunits of the GABAA receptor has revealed an unexpected heterogeneity which includes at least 4 homologous classes of subunits: these classes, designated as alpha, beta, gamma, and delta contain multiple variants. We have measured the steady-state levels of mRNAs encoding different (alpha 1, alpha 4, beta 1, beta 2, beta 3, gamma 2 long, gamma 2 short and delta) GABAA receptor subunits in the rat anterior pituitary and cerebellum using a polymerase chain reaction (PCR)-derived method. We found that pituitary cells express mRNAs encoding the alpha 1, beta 1 and beta 3 GABAA receptor subunits whereas the transcripts for alpha 4, beta 2 and delta were undetectable. We also found that pituitary cells selectively express the short isoform of the gamma 2 subunit mRNA. These data indicate that the expression of the various GABAA receptor subunits is cell-specific and support the concept that the diversity in function and pharmacology of the GABAA receptor is based on the ability of cells to specify the expression of selective GABAA receptor subunits.
Brain Res Mol Brain Res 1992 Mar
PMID:Rat pituitary cells selectively express mRNA encoding the short isoform of the y2 GABAA receptor subunit. 131 11

The hepatocyte nuclear factor 3 (HNF-3) gene family is composed of three proteins (alpha, beta, and gamma) that are transcription factors involved in the coordinate expression of several liver genes. All three proteins share strong homology in their DNA binding domains (region I) and are able to recognize the same DNA sequence. They also possess two similar stretches of amino acids at the carboxyl terminus (regions II and III) and a fourth segment of homology at the amino terminus (region IV). Furthermore, the HNF-3 proteins demonstrate homology with the Drosophila homeotic gene fork head in regions I, II, and III, suggesting that HNF-3 may be its mammalian homolog. In order to define HNF-3 beta protein domains involved in transcriptional activation, we have used a reporter gene, whose transcription is dependent on HNF-3 binding, for hepatoma cell cotransfection assays with expression vectors that produced different truncated HNF-3 beta proteins. A position-independent activation domain which contained conserved regions II and III was identified at the carboxyl terminus of the HNF-3 beta protein (amino acids 361 to 458). Moreover, site-directed mutations that altered the sequences within regions II and III demonstrated their importance to transactivation. The region II-III domain does not possess amino acid sequences in common with other transcription factors and may define a novel activation motif. HNF-3 beta amino-terminal sequences defined by conserved region IV also contributed to transactivation, but region IV activity required the participation of the region II-III domain. Region IV is abundant in serine amino acids and contains two putative casein kinase I phosphorylation sites, a feature similar to protein motifs described for the transcription factors Pit-1/GHF-1 and HNF-1.
Mol Cell Biol 1992 Sep
PMID:Hepatocyte nuclear factor 3 beta contains two transcriptional activation domains, one of which is novel and conserved with the Drosophila fork head protein. 132 4

The GABAA/benzodiazepine receptor consists of at least four subunits, alpha, beta, gamma and delta, each comprised of several variants. The developmental expression of the alpha 1, beta 1-3, gamma 2 and delta subunits was studied in the murine inferior olivary nucleus by in situ hybridization with antisense cRNA probes. The postnatal appearance and distribution of [3H]flunitrazepam and [3H]muscimol binding sites, alpha and beta subunit-specific ligands respectively, were also studied autoradiographically. The beta 3 subunit was transiently expressed in each of the subnuclei of the inferior olive: The signal was strong at birth, increased throughout postnatal week 1 and rapidly declined thereafter to low adult levels. A similar pattern of labeling was observed with [3H]muscimol. Detectable levels of alpha 1 subunit mRNA hybridization signal and [3H]flunitrazepam binding sites were also present in the inferior olive at birth, decreasing thereafter. Low to moderate levels of beta 1, beta 2, and gamma 2 subunit mRNAs were present in olivary neurons throughout postnatal development, while delta mRNAs were largely absent. It has been reported previously that, during the 2nd postnatal week, the ratio of climbing fiber terminals to Purkinje cells is reduced from 3:1, as observed in neonates, to the 1:1 relationship observed in the adult cerebellar cortex. Our results raise the possibility that the subunit composition of the GABAA/benzodiazepine receptor in inferior olivary neurons undergoes changes during development, and that this process may be related to the elimination of multiple climbing fiber innervation of cerebellar Purkinje cells.
Brain Res Mol Brain Res 1992 Dec
PMID:Ontogeny of GABAA/benzodiazepine receptor subunit mRNAs in the murine inferior olive: transient appearance of beta 3 subunit mRNA and [3H]muscimol binding sites. 133 34

The nicotinic acetylcholine receptor can be expressed in Xenopus oocytes by injection of in vitro synthesized RNA for the alpha, beta, gamma, and delta mouse muscle subunits. However, detectable responses can also be obtained by injection of alpha, beta, and delta subunit RNA only. The receptors expressed in this case (gamma-less receptors) share many of the properties of the normal receptor, including relaxation time constants, Hill slope, and relative permeability for Na+, K+, Cs+, and Tris+. The major single-channel conductances of alpha beta gamma delta and alpha beta delta receptors are similar (34.2 +/- 2.9 and 38.5 +/- 0.6 pS, respectively) but clearly different from the major conductances seen after the combined injection of alpha beta delta mouse subunit RNA and Xenopus gamma subunit RNA. Mutations in the second transmembrane segment of the alpha and beta subunits, known to affect open time and blockade by QX-222, are equally effective in the gamma-less receptor. These data strongly suggest that the gamma-less receptor has the same pore diameter as the normal receptor and that alpha, beta, and delta subunits participate in its formation. Injection of alpha beta gamma delta well as alpha beta delta RNA produced additional subconductance states of around 25 pS. The low conductance state was sensitive to mutations introduced in the alpha or beta subunits with or without the gamma subunit, indicating that this channel did not need the gamma subunits but required at least the alpha and beta subunits to be produced. Injection of alpha beta delta and the adult-type epsilon subunit RNA gave rise to channels with conductances of 35 and 55 pS when the stoichiometry of the injection was 2:1:1:1, but only the 55-pS channel was recorded when the epsilon subunit RNA concentration was increased by 10-fold (stoichiometry of 2:1:1:10). The gamma-less receptor can thus be expressed even when the adult epsilon subunit is present. Whether gamma-less receptors are expressed at normal adult neuromuscular junctions remains unknown.
Mol Pharmacol 1992 Apr
PMID:Structure of the gamma-less nicotinic acetylcholine receptor: learning from omission. 137

Thermodynamic parameters for the binding of hirudin to human alpha, beta and gamma-thrombin have been determined between pH 5.0 and 9.0, and from 10 degrees C to 40 degrees C; kinetic data for the association and dissociation of the proteinase-inhibitor complex were obtained at pH 7.5 and 21 degrees C. These results have been analysed in parallel with the inhibitor-binding properties of human alpha, beta and gamma-thrombin for the bovine basic pancreatic trypsin inhibitor (Kunitz-type inhibitor; BPTI). For the purpose of an homogeneous comparison, values of the apparent association equilibrium constant for BPTI binding to human gamma-thrombin have been determined between pH 5.0 and 9.0, at 21 degrees C. The different binding behaviour of hirudin and BPTI with respect to human alpha, beta and gamma-thrombin has been related to the inferred stereochemistry of the proteinase-inhibitor contact regions. In particular, whereas the beta and gamma-loops play an appreciable role in the stabilization of the enzyme-hirudin complexes, they contribute to impairment of the adduct formation for the proteinase/BPTI system.
J Mol Biol 1992 May 05
PMID:Binding of hirudin to human alpha, beta and gamma-thrombin. A comparative kinetic and thermodynamic study. 137 1


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