Abstract:
                                      To research the characteristics and structural features of 
BPI1 gene from channel catfish (
Ictalurus punctatus), total RNA was extracted from channel catfish kidney tissue and reversely transcribed into cDNA. Specific primers were designed to clone the 
BPI1 gene. Then 
BPI1 gene was inserted into the prokaryotic expression vector pTWIN1. The successfully constructed vector pTWIN1-
BPI1 was transformed into BL21 (DE3) competent cells for prokaryotic expression. According to the analysis of SDS-PAGE, the recombinant expression vector pTWIN1-
BPI1 successfully expressed a 50 kDa fusion protein, which conformed to the expected size. 
BPI1 gene sequence was studied by means of bioinformatics software. The results showed that 
BPI1 nucleotide sequence encoded 223 aa, with an isoelectric point (pI) of 9.07, and belonged to 
BPI superfamily. It was a stable and soluble protein. Subcellular localization of 
BPI1 was in the mitochondria (43.5%), cytoplasm (30.4%) and nucleus (26.1%), hence 
BPI1 may play a role in signal transducer or promote growth, especially in the energy metabolism and cofactor biosynthesis like purines and thymine. The secondary structure of 
BPI1 mainly consists of α-helices and beta-pleated sheet, besides, the tertiary structure of 
BPI1 was a rod-like structure. The amino acid sequence was highly conserved and shared the highest homology with 
BPI of channel catfish, along with sequences identities 99.1% and the same branch in the phylogenetic tree. Thus 
BPI1 gene sequence had lower mutation rate in the same species and had a strong conservative property that may have little impact on the bioactivity among individuals.