An open reading frame of the a-subunit 1-205 residues (alpha(205)) of human acetylcholine receptor (AchR) was amplified by PCR with pUC-AChRalpha(205) as the template and inserted into vector pMAL-c2X. The constructed pMARalpha(205) was transferred into E. coli BL21 which were then grown in LB medium. The amount of soluble MBP-AChRalpha(205) protein reached about 25% of total soluble proteins from the cell lysate. Using amylose-affinity chromatography, about 35 mg MBP-AChRalpha(205) could be obtained from I I culture. Western blot analysis and ELISA showed that immunoreactivities of both MBP-AChRalpha(205) and AChRalpha(205) were similar to that of AChR alpha-subunit from Torpedo.