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)

We investigated by molecular hybridization whether T cells contain RNA sequences homologous to RNA which codes for immunoglobulin kappa-chain (k-chain). A radioactive probe of complementary DNA (cDNA) was prepared by transcription of purified k-chain mRNA from mouse myeloma MOPC-41 with reverse transcriptase (RNA-dependent-DNA nucleotidyltransferase) from avian myeloblastosis virus. The cDNA probably corresponded only to the constant region and 3'-terminus of k-chain mRNA. Kappa-chain cDNA was found to hybridize efficiently with RNA from both thymus cells and an established culture of thymoma cells. The thymus and thymoma cells contained 99.8% and 100% theta-positive cells, respectively. Quantitatively the average thymus T cell (thymus derived lymphocyte) contained about one half as much k-chain mRNA as the average spleen B cell ("bursa" dependent lymphocyte), whereas the thymoma cells contained only 1/33 as much. Control hybridizations of k-chain cDNA with myeloma and liver RNA support the conclusion that T cells in the thymus and in the thymoma cell line synthesize k-chain mRNA-like molecules. The thermal stability of hybrids of k-chain cDNA with RNA from spleen, thymus, thymoma, and another k-chain producing myeloma tumor was lower than that with MOPC-41 RNA. This finding may be due to the existence of several slightly different ck genes in the mouse as suggested by various control experiments.
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PMID:Sequences related to immunoglobulin kappa chain messenger RNA in T cells. 82 Oct 55

DNA polymerase alpha is a DNA replicating enzyme expressed in all proliferating cells. This nuclear antigen in paraformaldehyde-postfixed frozen sections of normal, benign, and malignant tissues was identified by the peroxidase-antiperoxidase technique with the use of a mouse monoclonal antibody against bovine/human DNA polymerase alpha. The nuclei of normal proliferating cells were positive. Malignant tumors (n = 95) showed a higher proportion of positive nuclei than did low-grade malignant tumors (n = 7) or benign lesions (n = 67). The number of positive nuclei in squamous cell carcinomas (n = 19) was higher than in adenocarcinomas (n = 45). Eight (18%) adenocarcinomas and all five renal cell carcinomas had less than 10% positive cells, whereas in benign tissues, such as pituitary adenomas, a thymoma, reactive lymphoid lesions, and some benign mammary nodules, more than 10% of nuclei were labeled. In addition, foci of proliferating cells were clearly recognized. DNA polymerase alpha is, therefore, an excellent marker of proliferative activity that provides an approach to analyzing tumor cell heterogeneity not only in fully developed neoplasms, but also in their precursor lesions.
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PMID:DNA polymerase alpha. An immunohistochemical marker for proliferating cells in normal and neoplastic human tissues. 169 87

A DNA polymerase which was active with unprimed poly(dC) as a template was detected in the DNA polymerase alpha fraction from rat thymoma tissue. The activity was dependent on rGTP and associated with ribonucleotide polymerizing activity. The activity was partially sensitive to aphidicolin and dideoxy GTP and resistant to alpha-amanitin. Thus, this is a rat "replicase" which is very similar to that found in mouse cells. The replicase activity with poly(dT) or phage fd single stranded circular DNA was greatly enhanced by the mouse replicase-stimulating factor beyond the species difference.
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PMID:Detection of DNA replicase activity in rat thymoma cells. 684 30