Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed a method for the quantitation of apolipoprotein A-I (apoA-I) mRNA by using a variation of traditional S1 nuclease analysis. This method uses an internal standard RNA that allows a level of precision not obtainable with traditional S1 nuclease analysis. The internal standard RNA is synthesized in vitro using the T7 promoter from the transcription vector, pApoAI, which contains the full length apoA-I cDNA. This RNA molecule is identical to authentic apoA-I mRNA except for the addition of 48 bases at the 5'-end which are derived from the vector. A labeled ssDNA probe is produced from pApoAI in such a way that solution hybridization of the probe to a mixture of total RNA and internal standard RNA followed by S1 nuclease digestion results in the protection of DNA fragments from authentic and internal standard RNA, which differ in size by 48 bases. The DNA fragments can be resolved by gel electrophoresis and quantitated. The addition of internal standard RNA to each hybridization reaction allows for correction of variations in hybridization and other sources of experimental error. Using this method we demonstrate a sevenfold increase in precision (the 90% confidence interval was reduced from +/- 186% to +/- 26% of the mean value) when compared to traditional S1 nuclease analysis of apoA-I mRNA in liver biopsies and hepatocytes in culture. The internal standard/S1 nuclease method can be adapted to the analysis of any mRNA.
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PMID:An improved method for precise quantitation of cellular and tissue apolipoprotein A-I mRNA levels by use of an internal standard. 211 81

Since apolipoprotein A-I (apo A-I) and HDL stimulate the expression of the placental hormone human placental lactogen (hPL), experiments were performed to determine whether the human placenta synthesizes apo A-I. Western blot analysis of a partially purified extract of human term placenta with an antiserum to human apo A-I yielded an immunoreactive band with an apparent mass of approximately 23.5 kDa, which is smaller than human plasma apo A-I (28 kDa). HPLC chromatography of the partially purified placental extract on a preparative reverse-phase C-18 column yielded two fractions that reacted to the apo A-I antiserum. The mass of both fractions by mass spectral analysis was 22 721 daltons, and N-terminal amino acid sequences were identical to the first four amino acids of apo A-I (Asp, Glu, Pro, Pro). The apo A-I-like protein was not a proteolytic product of apo A-I since Northern analysis of placental RNA with a 641 bp apo A-I cDNA fragment encoding most of the 5' region of the apo A-I mRNA detected a single band of 850 nt, which is smaller than the size of apo A-I mRNA (1100 nt). Placental mRNA, however, did not hybridize with a 3' apo A-I riboprobe, indicating that the 3' region of the apo A-I-like mRNA is different from that of apo A-I mRNA. Differences in the mRNAs were confirmed by S1 nuclease analysis of placental RNA with a cDNA probe that included the 3' end of the apo A-I cDNA and by RT-PCR analysis with a series of oligonucleotide primers that span the entire cDNA for apo A-I. Since there is only a single apo A-I gene in the human genome, these findings strongly suggest that human placental tissue expresses a novel 22.7 kDa apo A-I-like protein (ALP) that results from alternative splicing of the apo A-I primary transcript.
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PMID:Human placental tissue expresses a novel 22.7 kDa apolipoprotein A-I-like protein. 865 39

The in vitro effect of tetrahydrocortisol-apolipoprotein A-I complex on native adult rat liver DNA results in the formation of S1 nuclease sensitive fragments that are irregularly distributed throughout a genome. Low-angle X-ray scattering showed that after the interaction with the tetrahydrocortisol-apolipoprotein A-I complex, DNA can bind to RNA-polymerase with a high and dose-dependent cooperativity. This indicates that the effect of tetrahydrocortisol-apolipoprotein A-I complex on secondary eukaryotic DNA structure causes a local denaturation of the double helix, promoting high cooperativity of binding to RNA-polymerase. The reduced form of the hormone, tetrahydrocortisol, previously considered as an inactive metabolite, when complexed with apolipoprotein A-I, promotes a biological function similar to that of a transcription factor.
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PMID:Effect of tetrahydrocortisol-apolipoprotein A-I complex on the secondary structure of eukaryotic DNA and its interaction with RNA-polymerase. 1213 78

A high affinity of apolipoprotein A-I for DNA and synthetic oligonucleotides was found using the affinity chromatography, affinity modification, and enzyme analysis. The competitive inhibition and Southern hybridization allowed disclosing the specificity of the interaction of the tetrahydrocortisol-apolipoprotein A-I complex (THC-ApoA-I) with high molecular weight DNA in regions contained GCC/CGG-sequences. The S1 nuclease sensitivity of the duplex CC(GCC)3 x GG(CGG)3 was found to occur under the action of THC-ApoA-I complex. The role of the interaction sites of eukaryotic DNA with steroid (THC, androsterone)-ApoA-I complexes in the initiation of the copy reaction in vitro was revealed.
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PMID:[Structure of the interaction sites of eukaryotic DNA with steroid hormone-apolipoprotein A-I complexes]. 1793 84