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)

The crossing over in five murine I-region recombinants (Is/Ik) was studied by restriction fragment length polymorphism analysis after Southern blot hybridization by using I-region-specific probes. These recombinants included three recently developed strains, B10.ASR1, B10.ASR11, and B10.ASR12; and two strains B10.S(9R) and B10.HTT derived earlier. Although these recombinants were reciprocal in haplotype orientation to the three recombinants we reported recently, these too crossed over within the same 7 kb stretch of DNA in the E beta gene. This 7 kb stretch of DNA included the 3' half of the first intron, the beta 1 exon, the second intron, and the beta 2 exon. A comparison of the cDNA sequences of the two parental E beta alleles revealed that although the beta 2 exons were identical, there were several nucleotide differences between the two beta 1 exons. This allowed us to determine the parental origin of the beta 1 exon in the recombinants at the level of transcription by using S1 nuclease mapping. Thus we were able to show that in each case the 3' portion of the first intron and the beta 1 exon were upstream from the site of crossover. All eight recombinants involving the k and s haplotypes now can be mapped within a 4.5 kb stretch of DNA, which includes only the beta 1-beta 2 intron and the beta 2 exon of the E beta gene. These findings imply that the I-E molecules expressed in these recombinants will probably have conserved sequences and therefore will exhibit identical I-E-restricted immune responses, despite the fact that crossing over could have occurred at different sites within the beta 1-beta 2 intron.
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PMID:Molecular mapping of murine I region recombinants. II. Crossing over in the E beta gene is restricted to a 4.5 kb stretch of DNA that excludes the beta 1 exon. 287 47

A lambda 1059 library of Phaseolus vulgaris cv. 'Tendergreen' DNA was screened with a cloned lectin-like cDNA. Among the phages selected was clone lambda B10 containing two complete lectin genes in the same orientation approximately 4 kb apart. The DNA sequences of the lectin genes and their flanking regions have been determined and their transcriptional initiation sites were located by S1 nuclease mapping. On the basis of the deduced amino acid sequences and compositions and the mol. wts. of their encoded glycoproteins, the genes, dlec1 and dlec2, are predicted to encode erythro- and leucoagglutinating phytohemagglutinins (PHA-E and PHA-L), respectively. The mRNA coding regions of dlec1 and dlec2 are 90% homologous, suggesting an origin involving duplication of an ancestral gene. Both lectin genes are intronless and have at least two ATG codons in a short (11-14 bp) 5'-untranslated region. Most of their 5'-untranslated regions consist of alternating pyrimidines and purines (RY repeats). Upstream sequences are also highly conserved between dlec1 and dlec2, including stretches of nine or more alternating R and Y residues. RY repeats of such length are not found within the protein coding portion of dlec1, dlec2 or a Phaseolus lectinlike gene previously described. Overlapping double (dlec1) or triple (dlec2) polyadenylation addition signals are found and there is an unusually high degree of homology (84%) between their 3'-untranslated regions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of two Phaseolus vulgaris phytohemagglutinin genes closely linked on the chromosome. 299 Sep 11