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R K Strair

Publications and source records attributed to R K Strair.

23 records · Page 2Linked to original sources
PubMed1978

Effect of a short term fast on the distribution of cytoplasmic albumin messenger ribonucleic acid in rat liver. Evidence for formation of free albumin messenger ribonucleoprotein particles.

Recently, using molecular hybridization techniques with albumin [3H]cDNA, we have determined that in normally fed rats 98% of total liver polyribosomal albumin mRNA sequences are found in membrane-bound polyribosomes (Yap, S. H., Strair, R. K., and Shafritz, D. A. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 5397-5401). We now observe that a 24- to 30-h withdrawal of food leads to major changes in the amount and subcellular distribution of albumin mRNA molecules. The total amount of cytoplasmic albumin mRNA per liver and concentration of albumin mRNA per unit of membrane-bound polyribosomal RNA are decreased. However, the proportion of albumin mRNA present in the postribosomal supernatant fraction increases dramatically in a short term fast, so that it now represent 60% of total cytoplasmic albumin mRNA sequences. Most of the albumin mRNA sequences in the postribosomal supernatant fraction sediment between 30 S and 50 S. These findings suggest that albumin mRNA is probably stored in the messenger ribonucleoprotein fraction during the fasting state.

Albumins↗
PubMed1978

Identification of a high molecular weight presumptive precursor to albumin mRNA in the nucleus of rat liver and hepatoma cell line H4AZC2.

Nuclear RNAs prepared from rat liver and rat hepatoma cell line H4AZC2 have been fractionated and examined for albumin mRNA sequences by annealing to specific albumin [3H]cDNA. In both instances, sucrose gradient analysis revealed nuclear RNA molecules containing albumin RNA sequences which sedimented at 26 S (26 S albumin RNA). In contrast, cytoplasmic albumin messenger RNA sediments exclusively at 17 S. 26 S albumin RNA is resistant to both heat denaturation (65 degrees C X 5 min) and denaturation in 85% formamide (v/v), and 75% of these molecules are polyadenylated. These results provide evidence for the existence of an intact, high molecular weight, polyadenylated nuclear RNA which contains albumin mRNA sequences.

Animals↗
PubMed1977

Use of molecular hybridization to purify and analyze albumin messenger RNA from rat liver.

A new procedure is described for purification of rat liver albumin mRNA. First a population of RNA molecules is enriched for albumin mRNA by immunoprecipitation of polysomes containing albumin nascent chains. Polyadenylylated RNA is prepared from immunoprecipitates, transcribed into complementary DNA, and shown to be enriched severalfold for a particular RNA frequency component. This enriched RNA component is then purified by molecular hybridization to a limited R(0)t value (product of RNA concentration and incubation time), under conditions in which only the most abundant sequence component is annealed. Potentially, this procedure can be employed for the purification of a wide variety of mRNAs present in lesser amounts in the cell. The isolated RNA appears to be a single frequency component by hybridization to complementary DNA transcribed from itself. This RNA is a 17S species and represents 5-8% of total cytoplasmic polyadenylylated RNA. In vitro translation of the purified RNA has shown that it codes for a single polypeptide that can be identified immunologically as albumin and migrates with rat serum albumin on sodium dodecyl sulfate/polyacrylamide gels. This albumin mRNA was determined to be essentially pure by comparing its kinetics of hybridization to those obtained with rabbit alpha + beta globin mRNA and its DNA complement. The sequence complexity of purified rat albumin mRNA corresponds to 5.9 x 10(5) daltons.

Albumins↗
PubMed1977

Distribution of rat liver albumin mRNA membrane-bound and free in polyribosomes as determined by molecular hybridization.

Recently, we purified rat liver albumin mRNA and prepared albumin [(3)H]cDNA. Using albumin [(3)H]cDNA in molecular hybridization experiments, we have now determined the distribution of albumin mRNA sequences in membrane-bound and free liver polyribosomes prepared by techniques in which there is high recovery of polyribosomes without evidence of degradation. By using molecular hybridization to measure specific mRNA sequence content, numerous problems could be avoided in interpretation of results as obtained by cell-free protein synthesis or immunological methods. Under these conditions, 98% of albumin mRNA sequences in polyribosomes are found in the membrane-bound fraction.

Albumins↗