Identification, genomic organization, and mRNA expression of LACTB, encoding a serine beta-lactamase-like protein with an amino-terminal transmembrane domain.
Database searching with bacterial serine beta-lactamases identified mouse expressed sequence tags (ESTs) with significant similarity scores.The cloned mouse cDNA encodes a novel 551-amino-acid protein, LACTB, with a predicted amino-terminal transmembrane domain but no signal peptide. It contains an active site motif related to C-class beta-lactamases. Homologues were detected in sequence data from human, rat, cow, rabbit, pig, toad, zebrafish, and Caenorhabditis elegans, but not in Saccharomyces cerevisiae or Drosophila melanogaster. The genes were mapped to human chromosome 15q22.1 and mouse chromosome 9. Sequencing of a 14.7-kb fragment of mouse genomic DNA defined six exons. A virtual human cDNA and a 549-residue protein, predicted from unfinished genomic sequence, showed the same intron/exon structure. Northern blot analysis showed expression of the 2.3-kb mRNA predominantly in mouse liver and human skeletal muscle. This is the first reported vertebrate example of this microbial peptidase family.
Smith
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Department of Genetics Research, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406, USA.
Southan
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Ellington
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Campbell
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Tew
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Debouck
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D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005091:Exons; D005260:Female; D015870:Gene Expression; D005796:Genes / Q000235:genetics*; D006801:Humans; D007438:Introns; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D026801:Synteny; D014018:Tissue Distribution; D001618:beta-Lactamases
C442861:Lactb protein, mouse; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D012269:Ribosomal Proteins; D004247:DNA; C486706:LACTB protein, human; D001618:beta-Lactamases