Peptide transporter Pept1 in Cyprinus carpio L.'s intestine: cDNA cloning and sequence analysis

Aim: To clone the Pept1 gene coding peptide transporter from the intestine of Cyprinus carpio L. and analyze its sequence. Material and Methods: A full-length cDNA encoding the Pept1 of Cyprinus carpio L. was cloned using RT-PCR and Rapid Amplification of cDNA Ends methods. We compared amino acid sequence of Pept1 with that of other 17 species and the sequences homology was analyzed using the Laser-gene analysis software package (DNAMAN 6.0, USA). The 3-D structure of the protein was predicted using comparative protein modeling program SWISS-MODEL. Results: The results showed that Cyprinus carpio L. Pept1 with 3118 bp was composed of 127 bp 5'-untranslated region, 819 bp 3'-untranslated region, and 2172 bp open reading frame. Pept1 could encode 723 amino acids with molecular weight of approximately 81.1 kDa and isoelectric point of 5.67. The predicted amino acid sequence has the highest similarity with that of zebra fish (80.9%), and the lowest similarity with that of sea urchin (40.5%). Twelve transmembrane domains were predicted in the 3-D protein model. Tyr-175 located in the fifth transmembrane domain and His-65 situated in the second transmembrane domain were essential for the catalytic activity of Pept1. Conclusion: The Cyprinus carpio L. Pept1 with 2172 bp open reading frame encodes 723 amino acids. The Pept1 contains 31.81% of alpha-helix, 23.65% of extended strand, 3.60% of beta-turn, 40.94% of random coil and twelve transmembrane domains. Pept1 gene has a highly conserved sequence.