To study the molecular mechanism of the small peptide transporter PepT1-mediated protein digestion and absorption, a full-length cDNA sequence of the using RT-PCR and RACE techniques. The full-length cDNA sequence of had 2762 nucleotides, including 141 nucleotides at 5′UTR and 479 nucleotides at 3′UTR. Its open reading frame had 2142 nucleotides encoding a 713-amino-acid peptide. The were most similar to those of at 77.6% and 74.0%, respectively; the deduced amino acid similarities were 78.0% and 76.7%, respectively; but the gene sequence varied in similarity to other animals from to 59.1%, and the deduced amino acid similarities were 60.5%—61.6%. The encoded protein molecular weight was predicted at The PepT1 protein had 11 helix trans-membrane regions; its amino acid sequence was highly homologous to those of other vertebrates. Phylogenetic analysis showed that the as its closest neighbor mRNA assayed by real-time PCR were differentially expressed by tissue type; the highest expression was in the foregut tissue and the second was in the muscle. However, mRNA expression was relatively stable after incubation for 7 days. The C. idellus. Its expression was higher during the night and lower during the day. This work provides a theoretical basis for the molecular mechanism of protein digestion and absorption by the small peptide transporter PepT1, which mediates intestinal transport of small peptides