Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The screening of a size-selected cDNA library from the ovary revealed the existence of a second form of PRL receptor in the rat. The polypeptide sequence deduced from cDNAs has a much longer cytoplasmic domain (357 amino acids) than the form previously identified in the liver (57 amino acids). Nucleotide sequence analysis and comparison with rabbit, mouse, and human PRL receptor cDNAs suggests that the two forms of rat PRL receptor result from alternative splicing of a primary transcript. Complementary DNAs encoding the long form of the receptor were also found in a library prepared from estradiol-treated rat liver, although they represent a minor fraction of total PRL receptor cDNAs obtained from this tissue. DNA polymerase chain reaction amplification of cDNA confirmed the presence of the two receptor forms in both the ovary and liver. Northern analysis, using probes that specifically hybridize with either form of mRNA, indicates a major transcript of 1.8 kilobases (kb) in estradiol-treated liver, which encodes the receptor with a short cytoplasmic domain, while the long form of the receptor is encoded by mRNAs of 2.5 and 3 kb. In the ovary, a complex pattern of hybridization to multiple mRNAs (1.8-5.5 kb) is obtained with the probe specific to the long form, and essentially only a 5.5-kb mRNA is obtained with the probe specific to the short form. The predicted size of the mature form of the long PRL receptor (PRL-R2) is 591 amino acid residues.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of two forms of prolactin receptor in rat ovary and liver. 229 22

bI1 RNA (excised from the first intron of the long form of the cytochrome b gene of Saccharomyces cerevisiae mitochondria) hybridizes with the two strands of a Bg/II-MboI DNA segment from this region. This fraction is resistant to digestions by DNase I and RNase T1 and disappears completely upon alkali hydrolysis. Strand-specific labeling of an intronic DNA fragment, cloned in pBR322 plasmid, was accomplished through the use of a T4 DNA polymerase. The purity of the probes was demonstrated by cloning an exon-intron fragment and labeling it by the same procedure; mRNA and pre-mRNA bands hybridized only with the transcribed DNA strand whereas bI1 RNA hybridized with the two strands under the stringent washing conditions employed (tm + 20 degrees C). Several experimental results argue against the possibility that the observation of two complementary bI1 RNA strands results from a partial self-complementarity of the RNA. A pre-mRNA intermediate from a box8 (G5046) mutant, still containing this intron, hybridizes only with the transcribed DNA strand of the pure intronic probe. The amount of the non-sense bI1 RNA strand is very low, in cells from two wild-type strains, relative to the sense RNA strand during the early stages of growth on glucose. It increases as the cells are released from glucose repression. bI1 RNA is resistant to RNase. Very little self-complementarity is seen by computer analysis of the sequence. Purified bI1 RNA is seen by electron microscopy under non-denaturing conditions as a mixture of double-stranded circular and linear molecules thus confirming the existence of the two complementary strands. The disappearance of all material following alkali hydrolysis demonstrates that these are indeed two RNA strands. Under fully denaturing conditions a mixture of single-stranded circular and linear molecules is seen as reported previously (Cell, 19, 321-329, 1980). We conclude that yeast mitochondria contain the two complementary bI1 RNA strands, one circular and the other linear. Considering a largely asymmetrical transcription of the mitochondrial genome in yeast and assuming that circularization of some intronic RNAs is part of RNA processing, we do not believe that the two strands are each a mixture of linear and circular molecules. The ratio of non-sense to sense bI1 RNA in a cytoplasmic petite mutant, A1B1, also varies according to growth conditions.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Yeast mitochondria contain a linear RNA strand complementary to the circular intronic bI1 RNA of cytochrome b. 620 24

The addition of nontemplated (N) nucleotides to coding ends in V(D)J recombination is the result of the action of a unique DNA polymerase, TdT. Although N-nucleotide addition by TdT plays a critical role in the generation of a diverse repertoire of Ag receptor genes, the mechanism by which TdT acts remains unclear. We conducted a structure-function analysis of the murine TdT protein to determine the roles of individual structural motifs that have been implicated in protein-protein and protein-DNA interactions important for TdT function in vivo. This analysis demonstrates that the N-terminal portion of TdT, including the BRCA-1 C-terminal (BRCT) domain, is not required for TdT activity, although the BRCT domain clearly contributes quantitatively to N-nucleotide addition activity. The second helix-hairpin-helix domain of TdT, but not the first, is required for activity. Deletional analysis also suggested that the entire C-terminal region of TdT is necessary for N-nucleotide addition in vivo. The long isoform of TdT was found to reduce N-nucleotide addition by the short form of TdT, but did not increase nucleotide deletion from coding ends in either human or rodent nonlymphoid cells. We consider these results in light of the recently reported structure of the catalytic region of TdT.
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PMID:Mutational analysis of terminal deoxynucleotidyltransferase-mediated N-nucleotide addition in V(D)J recombination. 1510 Feb 89