ORGANIZATION OF THE 5'-END OF THE PORCINE GAMMA-GLUTAMYL-TRANSPEPTIDASE GENE AND IDENTIFICATION OF 3 DIFFERENT MESSENGER-RNAS IN THE KIDNEY

Three different mRNAs coding for the porcine gamma-glutamyl transpepti dase (GGT) in the kidney were identified by 5'-RACE-PCR. These differ in their 5'-noncoding region. Genomic Southern blot analysis has demon strated the existence of a single GGT gene in the porcine genome. Thus , the existence of multiple mRNAs can only be explained by the use of different promoters or alternative splicing. Four GGT-specific genomic clones containing the complete 5'-end of the gene were isolated and c haracterized, revealing six exons common to all three mRNAs. Four of t hese exons were located in the coding region comprising the codons for amino acids 1 to 138. Two exons and an intervening sequence were iden tified upstream from these six common exons representing the unique 5' -ends of the three mRNAs. The coding exons show a significant sequence homology to mouse, rat, and human GGT cDNA, whereas exons 1 and 3 dis play no homology. (C) 1996 Academic Press