Abstract: ObjectiveGene P2X4R of Nile tilapia(Oreochromis niloticus)was cloned and its prokaryotic expression vector was constructed to induce its expression in order to lay a foundation for studying biological function of P2X4R in fish.MethodThree fragments(G1,G2 and G3)of gene P2X4R of Nile tilapia were cloned by PCR,then assembled into the target gene.The target gene linked pCold II vector to construct recombinant plasmid of pCold II-P2X4R.Bacillus coli BL21(DE3)competent cells were transformed to be induced by IPTG. The expression of recombinant protein P2X4R were detected by SDS-PAGE and Western blotting.Bio-informatics was used to analyze the physicochemical properties of protein P2X4R,glycosylation site,transmembrane region,subcellular localization and signal peptide.ResultGene P2X4R of Nile tilapia was cloned and its length was 1108 bp.The pCold II-P2X4R expression vector,which was constructed re-combinatly with pCold II vector,could obtain target protein after being induced by IPTG.The expression of recombinat protein induced by 1.0 mmol/L IPTG at 37℃for 4 h was higher than that induced by 0.1 mmol/L IPTG at 16℃overnight. Recombinat protein P2X4R contained 43.0 kD molecular weight and 354 amino acids.Its theoretical isoelectric point(pI) was 6.78,instability index 37.62 and aliphatic index 74.35,which meant it was stable protein.The recombinant protein P2X4R has three N-glycosylation sites and one O-glycosylation site.There was no transmembrane region in the protein, its protein sequence was almost 100% within the membrane. No signal peptide was observed.ConclusionNile tilapia protein is obtained by induction.It contains three N-glycosylation sites and one O-glycosylation sites.It is inferred that gly-cosylation phenomenon exists in it.Therefore,it could be used for preparation of relevant antibodies which can reveal an-tigen presentation of Nile tilapia macrophage.