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

Poly(C, U) random copolymer templates direct the oligomerization of 2-MeImpG and 2-MeImpA, resulting in the production of a variety of oligo/(G,A)s. The efficiency of monomer incorporation into newly synthesized oligomers is greater for 2-MeImpG than for 2-MeImpA, and decreases for both monomers as the uracil content of the template increases. The relatively poor incorporation of adenine is partly due to an intrinsically less efficient incorporation reaction, and partly due to the masking of uracil sites by G X U non-complementary pairing. The efficiency of adenine incorporation can be improved by decreasing the concentration of 2-MeImpG and increasing the concentration of 2-MeImpA in the reaction mixture. The oligomeric product distribution can be characterized in detail using high-pressure liquid chromatography on an RPC-5 column. Oligomers are separated on the basis of chain length, base composition, and phospho-diester-linkage isomerism. The 3'----5' regiospecificity of monomer addition to template-bound oligomers is lower for 2-MeImpA than for 2-MeImpG. The presence of an adenine residue at the 2'(3') terminus of the acceptor strand lowers the regiospecificity of 2-MeImpA addition even further.
J Mol Biol 1984 Jun 25
PMID:Non-enzymatic template-directed synthesis on RNA random copolymers. Poly(C, U) templates. 620 54

Poly[d(A-T)].poly[d(A-T)], when reconstituted with chicken erythrocyte core histones and subsequently incubated with sufficient histone H5 in a solution containing polyglutamic acid, forms structures resembling chromatin. H5 induces nucleosome alignment in about two hours at physiological ionic strength and 37 degrees C. The nucleosome spacing and apparent linker heterogeneity in the assembled nucleoprotein are very similar to those in chicken erythrocyte chromatin. Also, condensed chromatin-like fibers on the polynucleotide can be visualized. The binding of one mole of H5 per mole of core octamer is necessary to generate the physiological nucleosome spacing, which remains constant with the addition of more H5. The nucleosome repeat length is not a function of the core histone to poly[d(A-T)] ratio for values lower than the physiological ratio. With increasing ratios, in excess of the physiological value, nucleosome spacing first becomes non-uniform, and then takes on the close packing limit of approximately 165 base-pairs. In addition to eliminating possible base sequence effects on nucleosome positioning, poly[d(A-T)] allows nucleosomes to slide more readily than does DNA, thereby facilitating alignment. Evidence is presented that polyglutamic acid facilitates the nucleosome spacing activity of histone H5, primarily by keeping the nucleoprotein soluble. This model system should be useful for understanding how different repeat lengths arise in chromatin.
J Mol Biol 1984 Sep 15
PMID:A model chromatin assembly system. Factors affecting nucleosome spacing. 620 68

Earlier studies have shown that idiotype-specific T suppressor cells can directly inhibit the biosynthesis and subsequent secretion of immunoglobulin from the BALB/c myeloma, MOPC-315. This suppression is highly specific and does not affect nonimmunoglobulin protein synthesis in these cells. The selective character of this suppression suggested a transcriptional or translational mechanism of control. Therefore, we analyzed suppressed MOPC-315 cells for the expression of light and heavy chain mRNAs. Since the events that occur in a B cell subsequent to reception of suppressive signals from T cells are presently unknown, these experiments address a fundamental aspect of B cell regulation. Another important aspect of these studies is that they deal with a suppressor T cell that clearly operates directly upon the antibody-secreting cell. This system involves regulation of a B cell differentiative function without influencing the B cell clonal size. We have employed the trinitrophenyl (TNP)-specific myeloma, MOPC-315, because it provides a source of monoclonal B cells which in earlier studies have been shown to be responsive to idiotype-specific and TNP-antigen-specific immunoregulatory signals. The idiotype-specific T cells were generated by hyperimmunizing BALB/c mice with the myeloma protein bearing the 315 idiotype, in complete Freund's adjuvant. Poly A+ mRNA was isolated from MOPC-315 cells following coculture with either normal or idiotype-immune T cells. The mRNA was analyzed using hybridization techniques and cDNA probes specific for alpha or lambda 2 light chain constant regions.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Cell Immunol 1984
PMID:Idiotype-specific T cell suppression of light chain mRNA expression in MOPC-315 cells is accompanied by a posttranscriptional inhibition of heavy chain expression. 624 51

The steroid hormone ecdysterone induced characteristic and specific changes of morphology, enzymatic activities and protein synthesis in a Kc 0% Drosophila melanogaster cell line. To study the ecdysterone action at a molecular level, a Drosophila genomic library was screened by differential hybridization to poly(A)+ RNA from control and ecdysterone-treated cells. Two recombinant phages were selected for hybridizing very intensively with poly(A)+ RNA of ecdysterone-treated cells and very weakly with poly(A)+ RNA of untreated ones. These two clones (lambda Dm 1632 and lambda Dm A5A1) mapped at the 5 C locus on polytene chromosomes; they overlap for a 9000 base-pair sequence that contains an abundantly transcribed region in ecdysterone-treated cells of about 2000 base-pairs. This region permits the selection of mRNA that gives, after translation in vitro, two polypeptides identified as cytoplasmic actin II and III. We demonstrated that these two recombinant phages, hybridizing preferentially with poly(A)+ RNA of ecdysterone-treated cells, contain the 5 C actin gene. Poly(A)+ RNA prepared from various times of treatment of cells were electrophoresed on agarose gels, transferred to nitrocellulose paper and then hybridized with the cloned actin probe. Results of these experiments indicate that there is a sharp increase in the level of RNA coding for actin after ecdysterone treatment of the cell, and that there are two forms of actin-specific RNA in the D. melanogaster cells. Using genomic blots with specific probes derived from lambda Dm 1632, we show that there are six actin genes per haploid Drosophila cell genome contained on six EcoRI fragments, as in Drosophila embryos, indicating that there is no rearrangement of these sequences in cultured cells. Our results suggest that the expression of actin genes in D. melanogaster Kc 0% cells is modulated by ecdysterone.
J Mol Biol 1983 Mar 05
PMID:Actin gene expression is modulated by ecdysterone in a Drosophila cell line. 630 76

Human simian virus 80 (SV80) cells transformed by simian virus 40 (SV40) synthesize substantial quantities of the SV40 large T-antigen (Henderson & Livingston, 1974; Tjian, 1978) and cytoplasmic, poly(A)-containing RNA species that exhibit spliced structures characteristic of the SV40, early messenger RNA species that encode both large and small T-antigens (Flint & Beltz, 1979). When SV80 cells were infected with type C adenovirus, both the synthesis of SV40 large T-antigen and the appearance in the cytoplasm of newly synthesized, SV40-specific RNA sequences were inhibited during the late phase of infection. The results of hybridization to SV40 DNA of SV80 nuclear RNA, prepared from mock- or adenovirus-infected cells after labeling for short periods in vivo or in vitro, indicated that transcription of integrated SV40 was, by contrast, not disrupted during the late phase of adenovirus infection. Poly(A)-containing, nuclear RNA species that hybridized to SV40 DNA sequences and exhibited the sizes of spliced, large and small T-antigen mRNA species were also synthesized in infected cells at a time when the corresponding mRNA sequences did not leave the nucleus. These results suggest that the failure of non-adenoviral mRNA sequences to enter the cytoplasm of adenovirus-infected cells does not reflect inhibition of either their transcription or the normal enzymatic processing reactions to which pre-mRNA species are subject. Several lines of evidence do, however, establish that nuclear, SV40-specific RNA sequences are less stable in adenovirus-infected compared to mock-infected SV80 cells.
J Mol Biol 1983 Jun 25
PMID:Synthesis and processing of simian virus 40-specific RNA in adenovirus-infected, simian virus 40-transformed human cells. 630 59

A cDNA cloning approach was used to study the regulation of gene expression in human T lymphocytes upon mitogen stimulation. Poly(A)+ mRNA was prepared from phytohemagglutinin A (PHA) and 12-O-tetradecanoyl phorbol 13-acetate (TPA) activated human T cells and a cDNA clone library was constructed. After screening by colony hybridization with [32P]cDNA probes made from resting and activated T cell mRNA, several clones whose mRNA increased at least 10 to 20-fold upon stimulation were isolated. Northern blot analysis of the mRNA from various cell types using these cDNA clones as probes revealed that one of the cDNA clones, pNC5A, encoded a gene expressed only in PHA and TPA-stimulated human T lymphocytes and in a human neoplastic T cell line HUT102-SH9. Less than 20 copies of this mRNA species per cell was detected in resting human T lymphocytes, B lymphocytes and monocytes and in two other T cell lymphoma lines (CEM and MOLT4), two B lymphoblastoid cell lines (WIL2-729-HF2 and HFB-1), a myeloid cell line (HL60) and a human embryonic lung fibroblast cell line (MRC-5). Hybrid selection translation and sodium dodecyl sulfate/polyacrylamide gel electrophoretic analysis of the translated product indicated that a polypeptide of 30,000 to 32,000 Mr is encoded by this particular cDNA clone. Thus, this cDNA clone may define a novel gene that is expressed only in activated human T cells.
Mol Biol Med 1984 Apr
PMID:A cDNA clone encoding a product of activated human T lymphocytes. 633 9

A naturally occurring variety of soybean Glycine max cv. Keburi, which lacks the alpha'-subunits of the 7S seed storage protein (beta-conglycinin), was recently described by Kitamura and Kaizuma. Keburi beta-conglycinins contain a normal complement of alpha-, beta-, and gamma-subunits that accumulate in a temporally and spatially regulated manner comparable to that of the standard cultivar Provar. Poly(A)+ RNA isolated from mid-to-late maturation stage Keburi seeds was translated in vitro, yielding products equivalent to those of Provar poly(A)+ RNA except that Keburi mRNA did not produce the pre-alpha'-subunit polypeptide. The basis of the Keburi phenotype was determined by examining genomic DNA using Southern blot hybridization. Restriction fragments isolated from a cloned 11.5 kb EcoRI fragment of genomic DNA containing a normal alpha'-subunit gene (Gmg 17.1) were used as hybridization probes. Sequences far upstream of the alpha'-subunit gene were present in both Provar and Keburi cultivars. However, hybridization reactions with probes from within the gene demonstrated that a deletion had occurred in Keburi DNA beginning immediately 5' to the alpha'-subunit gene represented on this 11.5 kb fragment. The deletion extends through most of the coding sequences, producing the Keburi phenotype.
J Mol Appl Genet 1984
PMID:Molecular characterization of a deletion mutation affecting the alpha'-subunit of beta-conglycinin of soybean. 653 3

Poly(A+)-containing mRNA from human term placenta was used to direct protein synthesis in a nuclease-treated rabbit reticulocyte lysate, which is dependent on mRNA and tRNA for maximal activity. The major protein product was human pre-placental lactogen (hPL). Addition of tRNA from rabbit liver, rabbit reticulocyte, human first trimester and term placenta, human liver and yeast resulted in 2-5-fold stimulation of [35S]methionine incorporation into total protein. Although all mammalian tRNA increased hPL synthesis, the relative synthesis as compared to endogenous globin was markedly different and most efficient with tRNA from term placenta. Addition of yeast tRNA increased total incorporation 3-fold but decreased incorporation of [35S]methionine into pre-hPL. These results suggest that the population of isoacceptor tRNAs may influence the expression of hPL in term placenta. Results are discussed by showing codon bias and usage of mRNA coding for hPL, alpha- and beta-hCG, rabbit globin and yeast alcohol dehydrogenase I.
Mol Cell Endocrinol 1983 Feb
PMID:Effect of transfer RNA from various sources on placental messenger RNA translation. 683 70

Undegraded Vicia faba polysomes from meristematic root cells were obtained after homogenization in a medium of low ionic strength provided that the pH was equal to 9.0. By minimizing the shearing forces during the homogenization step, polysomes were obtained free of mitochondrial and nuclear contaminants, measured by differential spectrophotometry and CsCl gradient centrifugation respectively. Poly(A)-containing RNA was obtained by poly(U)-Sepharose chromatography and shown to be virtually free of rRNA and its average size was 13-15 S. Approximately 9% of the purified preparation was annealed by [3H]-poly(U). Sucrose gradient analysis under denaturing conditions showed that the poly(A)-CONtaining RNA were non-degraded. This RNA was used to direct the synthesis of proteins in a heterologous cell-free system from wheat germ.
Mol Cell Biochem 1980 Feb 28
PMID:Isolation and characterization of polysomes and polyadenylated polysomal RNA from Vicia faba meristematic root cells. 737 55

Following a standard heat shock, approximately 40% of Hsp70 transcripts in Drosophila melanogaster lack a poly(A) tail. Since heat shock disrupts other aspects of RNA processing, this observation suggested that heat might disrupt polyadenylation as well. We find, however, that as the temperature is increased a larger fraction of Hsp70 RNA is polyadenylated. Poly(A)-deficient Hsp70 RNAs arise not from a failure in polyadenylation but from the rapid and selective removal of poly(A) from previously adenylated transcripts. Poly(A) removal is highly regulated: poly(A) is (i) removed much more rapidly from Hsp70 RNAs than from Hsp23 RNAs, (ii) removed more rapidly after mild heat shocks than after severe heat shocks, and (iii) removed more rapidly after a severe heat shock if cells have first been conditioned by a mild heat treatment. Poly(A) seems to be removed by simple deadenylation rather than by endonucleolytic cleavage 5' of the adenylation site. During recovery from heat shock, deadenylation is rapidly followed by degradation. In cells maintained at high temperatures, however, the two processes are uncoupled and Hsp70 RNAs are deadenylated without being degraded. These deadenylated mRNAs are translated with low efficiency. Deadenylation therefore allows Hsp70 synthesis to be repressed even when degradation of the mRNA is blocked. Poly(A) tail shortening appears to play a key role in regulating Hsp70 expression.
Mol Cell Biol 1994 Jun
PMID:Preferential deadenylation of Hsp70 mRNA plays a key role in regulating Hsp70 expression in Drosophila melanogaster. 751 48


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