Molecular structure and alternative splicing of the human carboxypeptidase M gene

Using RACE technology the 5' and 31 ends of human carboxypeptidase M (CPM) mRNA were determined and found to be divergent from the published sequence. With these results the complete structure of the human CPM gene was established based on the human genome sequence in the GenBank database. the gene was shown to contain 9 exons comprising at least 75 kb of genomic sequence. A novel first exon of 30 bp was identified and an upstream promoter sequence containing several transcription factor binding sites was found by computer analysis. Furthermore, the ATG starting codon was detected defining an open reading frame of 1329 bp that codes for a protein of 443 residues. Additionally, the polyadenylation site was discovered, determining a 31 noncoding region of 2000 nucleotides. the exon-intron boundaries diverged substantially compared to those of the other basic carboxypeptidases, CPD, CPE, CPN, and AEBP1. Cloning and sequencing of RT-PCR products from different tissues revealed alternative splicing of exons 3 and 5, which results in the generation of four different mRNA isoforms. RNA extracted from tumor tissues contained more CPM mRNA than control tissue, suggesting an upregulation of CPM expression in tumors and raising the question of the role of this enzyme in cancer.Max Delbruck Ctr Mol Med, D-13092 Berlin, GermanyUniversidade Federal de São Paulo, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Gynecol & Genet, BR-04301900 São Paulo, BrazilUniversidade Federal de São Paulo, CEDEME, Ctr Dev Expt Models Med, BR-04023062 São Paulo, BrazilUniv Fed Minas Gerais, Dept Physiol & Biophys, BR-31270901 Belo Horizonte, MG, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Gynecol & Genet, BR-04301900 São Paulo, BrazilUniversidade Federal de São Paulo, CEDEME, Ctr Dev Expt Models Med, BR-04023062 São Paulo, BrazilWeb of Scienc