Objective: To clone

express

and identify the extracellular domain gene of human p75 neurotrophin receptor with IgG-Fc （hp75NTR-Fc） in prokaryotic expression system

and investigate the effect of the recombinant protein on dorsal root ganglia （DRG） neuron neurites. Methods: The hp75NTR-Fc coding sequence was amplified from pcDNA-hp75NTR-Fc by polymerase chain reaction （PCR） and subcloned into vector pET30a （+）

in which hp75NTR-Fc expression was controlled under the T7 promoter. The recombinant vectors were amplified in E. coli DH5α and identified by PCR

enzyme digestion and sequencing

and then transformed into E. coli BL21 （DE3）. The expression product was analyzed with SDS-PAGE and Western blot. Then after the recombinant protein purified with Protein A affinity chromatograph

and renaturated with dialysis

respectively

the effect of the recombinant protein on DRG neuron neuritis was further investigated. Results: The results of PCR

enzyme digestion

and sequencing demonstrated the success of inserting the hp75NTR-Fc fragment into vector pET30a （+）. SDS-PAGE and Western blot showed a positive protein band with molecular weight about 50 kD in the expression product

which is accordant with the interest protein

and this band could be specifically recognized by rabbit anti-NGFRp75 antibody. The purified infusion protein following dialysis could promote neurite outgrowth of DRG neurons cultured with myelin-associated glycoprotein （MAG）. Conclusion: The hp75NTR-Fc coding sequence was subcloned into the expression vector pET30a （+） correctly and expressed successfully in the prokaryotic expression system. The infusion protein could promote neurite outgrowth of DRG neurons cultured with MAG.