Cloning and characterization of the novel gene for mast cell carboxypeptidase A.
No gene for a hematopoietic cell carboxypeptidase has previously been characterized. Mast cell carboxypeptidase A (MC-CPA) is a prominent secretory granule marker of mast cell differentiation and phenotype. The 32-kb human MC-CPA gene was isolated, localized to chromosome 3, and found to contain 11 exons. No significant homology was found between the 5' flanking region of the MC-CPA gene and those of three rat pancreatic carboxypeptidase genes (carboxypeptidase A1 and A2, and carboxypeptidase B [CPB]). In contrast, the intron/exon organization of the MC-CPA gene was conserved, most closely resembling the CPB gene. MC-CPA is unique among carboxypeptidases in having a CPA-like substrate-binding pocket and enzymatic activity despite overall protein and gene structures more similar to CPB. Evolutionary tree analysis of the carboxypeptidase gene family showed that, before the mammalian species radiation, a common MC-CPA/CPB ancestor diverged by gene duplication from the lineage leading to CPA, and then underwent another gene duplication to form separate but similar gene structures for MC-CPA and CPB. MC-CPA mRNA was prominent in dispersed lung cells enriched for mast cells but was undetectable in other nontransformed populations of several lineages, demonstrating that transcription of MC-CPA, a novel carboxypeptidase gene, provides a specific molecular marker for mast cells among normal hematopoietic cell populations.
Reynolds
D S
DS
Department of Medicine, Harvard Medical School, Boston, Massachusetts.
Gurley
D S
DS
Austen
K F
KF
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002268:Carboxypeptidases / Q000235:genetics*; D043422:Carboxypeptidases A; D002874:Chromosome Mapping; D002893:Chromosomes, Human, Pair 3 / Q000648:ultrastructure; D003001:Cloning, Molecular; D015870:Gene Expression; D006801:Humans; D008322:Mammals / Q000235:genetics; D008407:Mast Cells / Q000201:enzymology*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009928:Organ Specificity; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D002268:Carboxypeptidases; D043422:Carboxypeptidases A