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)

A simple method for generating cDNA libraries from submicrogram quantities of mRNA is described. It combines classical first-strand synthesis with the novel RNase H-DNA polymerase I-mediated second-strand synthesis [Okayama, H., and Berg, P., Mol. Cell. Biol. 2 (1982) 161-170]. Neither the elaborate vector-primer system nor the classical hairpin loop cleavage by S1 nuclease are used. cDNA thus made can be tailed and cloned without further purification or sizing. Cloning efficiencies can be as high as 10(6) recombinants generated per microgram mRNA, a considerable improvement over earlier methods. Using the fully sequenced 1300 nucleotide-long bovine preproenkephalin mRNA, we have established by sequencing that the method yields faithful full-length transcripts. This procedure considerably simplifies the establishment of cDNA libraries and thus the cloning of low-abundance mRNAs.
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PMID:A simple and very efficient method for generating cDNA libraries. 619 42

All of the endogenous opioid peptides thus far identified are derived from three types of precursors, i.e. the corticotropin/beta-lipotropin precursor, preproenkephalin A and preproenkephalin B. Poly(A)-containing RNA from various bovine and porcine tissues has been subjected to blot hybridization analysis with the use of cDNA probes specific for the three opioid peptide precursors. Analysis with a corticotropin/beta-lipotropin precursor cDNA probe has revealed, in addition to the pituitary mRNA, a smaller hybridizable RNA species present in bovine extrapituitary tissues, such as the adrenal medulla, thyroid, thymus, duodenum and lung. The hypothalamus contains both these RNA species. DNA complementary to the smaller RNA species from the bovine adrenal medulla has been cloned. Analysis of the cloned cDNA, in conjunction with endonuclease S1 mapping of poly(A)-rich RNA from the adrenal medulla, has indicated that the smaller RNA species represents the 3'-terminal 712-729 nucleotides, excluding the poly(A) tail, of the pituitary corticotropin/beta-lipotropin precursor mRNA, having heterogeneous start sites. Analysis with a preproenkephalin A cDNA probe has shown the presence of hybridizable RNA in the bovine hypothalamus, duodenum and pituitary neurointermediate lobe in addition to the adrenal medulla. The hybridizable RNA species from all these tissues are indistinguishable in size. RNA hybridizable with a preproenkephalin B cDNA probe has been found in the porcine spinal cord and ileum besides the hypothalamus, and these RNA species exhibit an indistinguishable size. The results presented indicate that each opioid peptide precursor is synthesized in different tissues.
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PMID:Tissue distribution of messenger RNAs coding for opioid peptide precursors and related RNA. 633 21