Identification and characterization of adult alpha-and beta-globin genes and their genomic arrangement in Pseudosciaena crocea

The α-and β-globin genes from Pseudosciaena crocea were cloned by rapid amplification of cDNA 3'-end (3'-RACE). The cDNA of the α-globin is 595 bp with the ATG start codon located at Position 37, the TAA stop codon at Position 469 and the AATAAA polyadenylation signal at Position 560, which codifies 145 amino acids. The entire open reading frame of the β-globin gene is 447 bp long, which encodes 148 amino acids. Amino acid identity of the α-globin or β-globin gene compared with those reported in other fish species, ranged from 31.9% to 76.4%. When comparing with human α-and β-globins, three important alterations in the structural regions can be noted:α39 Thr→Gln, α113 His→Tyr and β117 His→Lys. The α-globin has a unique inserted amino acid residue in the 47th position. To understand the process of globin gene duplication and identify the regulatory elements present in the intergenic and intragenic regions of globin genes, the genomic arrangement of α-and β-globin genes was investigated. The results showed that the orientation of the two genes was head-to-head relative to each other. The intergenic region between the translation initiation codons of the linked α-and β-globin genes contains classical promoter elements and the length of it is much shorter than that reported in other fish.