Molecular cloning and characterization of mouse mast cell chymases.
Mouse mast cell chymases are granule-associated serine proteinases with chymotrypsin-like substrate specificities. cDNAs for two new chymases were isolated from a cDNA library constructed using mRNA from ABFTL-6 mouse mast cells by screening with a rat mast cell proteinase cDNA. The deduced amino acid sequence of mouse chymase 1 consists of a 226 amino acid catalytic portion and a 21 amino acid preprosequence. Chymase 1 is unusual in that an Asn occurs in the substrate binding pocket, a feature that has not been observed in any other serine proteinase. Also, chymase 1 is expected to have a large positive charge (+13) at physiological pH. A partial cDNA for chymase 2 encodes 177 residues of the carboxy terminal portion of a second proteinase distinct from chymase 1. Chymase 2 cDNA contains a highly conserved intron/exon junction, a high positive charge (+17) and a novel, second potential N-glycosylation site. Transcripts for both chymases are found in ABFTL-6 mast cells, but only chymase 2 mRNA is in mouse connective tissue mast cells. These data suggest that these chymases have distinct enzymatic properties and tissue-specific patterns of gene expression.
Chu
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Department of Biochemistry, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614-0581.
Johnson
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Musich
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D053818:Chymases; D003001:Cloning, Molecular / Q000379:methods; D004285:Dogs; D015723:Gene Library; D006031:Glycosylation; D007527:Isoenzymes / Q000235:genetics*; D008407:Mast Cells / Q000201:enzymology*; D051379:Mice; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D012697:Serine Endopeptidases / Q000235:genetics*
D007527:Isoenzymes; D021382:Protein Sorting Signals; D012313:RNA; C509227:Cma1 protein, mouse; D012697:Serine Endopeptidases; D053818:Chymases; C509228:Cma1 protein, rat; C509229:Cma2 protein, mouse