Aim: To fusion and express the extracellular of human aquaporin 4( AQP4) in prokaryotic cells,and purify and identify the expressed products. Methods: The sequences of the extracellular of human AQP4 were designed according to the E. coli preferred codons and the necessary of the experiment,synthesized,annealed and cloned into vector p ET32a( +). The recombinant plasmids were transformed to E. coli BL21( DE3) for expression under induction of IPTG.The expressed fusion proteins were purified by nickel ion af...