Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of TCR-beta mRNAs competent to encode functional V(D)JC beta proteins requires the activation of programmed DNA rearrangement events. It is not known whether other regulatory mechanisms control the steady-state levels of mature TCR-beta transcripts during thymic ontogeny. In this report, we demonstrate that TCR-beta pre-mRNAs accumulate in T cells, thus implicating RNA splicing as another potential level of regulation. Three methods were used to characterize the intron content of these pre-mRNA: Northern blot analysis, ribonuclease H mapping, and reverse transcription polymerase chain reaction analysis. Using these methods, we demonstrate that intron-containing TCR-beta transcripts derived from both the JC beta 1 and JC beta 2 loci accumulate in murine fetal and adult thymus. (VD)JC beta 1 pre-mRNAs that accumulate in the thymus possess unusually long poly(A) tails (> or = 300 nucleotides) and contain different combinations of four introns: the large intron between the J beta 1 and C beta 1 elements and the three introns within the C beta 1 element. The presence of an unusual transcript possessing IVS2C beta 1 at the 5' terminus suggests that cleavage of its splice acceptor is inefficient or negatively regulated. The profile of incompletely spliced TCR-beta transcripts present in the thymus in vivo is identical in intron content to those that we previously showed accumulate in the nucleus of the immature SL12.4 T lymphoma cell clone. An unstable negative regulatory protein may control TCR-beta expression in this cell clone because fully spliced TCR-beta transcripts are dramatically induced in the cytoplasm after treatment with any of five different protein synthesis inhibitors (cycloheximide, anisomyosin, emetine, puromycin, and pactamycin), all of which act by distinct mechanisms to inhibit protein synthesis.
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PMID:T cell receptor-beta mRNA splicing during thymic maturation in vivo and in an inducible T cell clone in vitro. 790 99

A single polypeptide of the HIV-1 reverse transcriptase that reconstituted Mg(2+)-dependent RNase H activity has been made. Using molecular modeling, the construct was designed to encode the p51 subunit joined by a linker to the thumb (T), connection (C), and RNase H (R) domains of p66. This p51-G-TCR construct was purified from the soluble fraction of an Escherichia coli strain, MIC2067(DE3), lacking endogenous RNase HI and HII. The p51-G-TCR RNase H construct displayed Mg(2+)-dependent activity using a fluorescent nonspecific assay and showed the same cleavage pattern as HIV-1 reverse transcriptase (RT) on substrates that mimic the tRNA removal required for second-strand transfer reactions. The mutant E706Q (E478Q in RT) was purified under similar conditions and was not active. The RNase H of the p51-G-TCR RNase H construct and wild type HIV-1 RT had similar K(m)s for an RNA-DNA hybrid substrate and showed similar inhibition kinetics to two known inhibitors of the HIV-1 RT RNase H.
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PMID:Expression of an Mg2+-dependent HIV-1 RNase H construct for drug screening. 2176 6

Single-cell sequencing of TCR alleles enables determination of T cell specificity. Here we describe a sensitive protocol for targeted amplification of TCR CDR3 regions from single-cell full-length cDNA libraries. By exploiting the specificity of RNase H-dependent PCR (rhPCR), the protocol achieves amplification of TCR alleles and addition of cell barcodes in a single PCR step.
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PMID:Targeted TCR Amplification from Single-Cell cDNA Libraries. 3102 40