Genomic structure of ornithine carbamoyltransferase gene from Canavalia lineata

The nucleotide sequences of the complete ornithine introduction carbamoyltr ansferase (OCT) gene containing 3,964 bp 3' region and 1,701 bp promoter re gion were determined from Canavalia lineata leaves. The exons range in size from 131 bp to 390 bp, while the introns range in size from 102 bp to the relatively large size of 1,465 bp; all the splicing junctions followed the conserved GT/AG rule. The transcription initiation site is located 12 bp up stream of the ATG translation initiation site and 69 bp downstream of TATA- box, The regulatory elements located in the 1,701 bp 5' upstream region are GT-1, GATA moth, I-box, SBF-1, Nit2 etc, The structure of the OCT gene fro m C. lineata was compared with Arabidopsis thalinna, in which two genes con sist of 5 exons and 4 introns. The nucleotide sequence of exons and deduced amino acid sequence exhibits 70% and 69% homology, respectively. The deduc ed amino acid sequences show identical conserved "HPXQ" box, carbamoyl phos phate and ornithine binding sites, The introns of C. lineata OCT gene are l arger than those of A, thaliana, except for intron 3, Genomic DNA blot anal ysis showed that a single ornithine-dependent OCT gene exists in the C. lin eata genome.