Abstract: 　Objective To identify the putative regulation elements with strength- and stage- specificity in 5′ proximal flanking sequence of P.falciparum GBP130 gene. Methods Plasmids containing different deletions of upstream of the GBP 130 promoter were constructed. For strength-specific analysis, pGBPCATΔ2, pGBPΔ2/400 and pGBPΔ2/800 were electroporated into ring-stage P.f. respectively, and the expression level of CAT in each plasmid was detected by liquid scintillation counts(LSC). For stage-specific analysis, transfectants with pGBPΔ2/400 and pGBPΔ2/800 were harvested at 5 hours post-transfection(h), 15 h and 46 h respectively, and the CAT expression levels were detected. Results In strength-specific analysis, the expression level of CAT in pGBPΔ2/800 and pGBPCATΔ2 was similar, down-regulated significantly in pGBPΔ2/400. The CAT level showed significant difference between pGBPΔ2/400 and the control. In stage-specific analysis, the CAT level of pGBPΔ2/400 was higher than that of pGBPΔ2/800 at the time point of 5 h, and lower at 15 h and 46 h. Conclusion This strength-specific promoter activity was due to the difference of 5′UTR length:the longer the 5′UTR the higher the promoter strength, and two poly (dA∶dT) tracts in the proximal sequence could enhance the promoter activity. The length of 5′UTR regulated the promoter activity in a stage-specific manner. The shorter 5′UTR was functional at ring stage, while the longer one prompted transcription at trophozoite and schizont stage. The functional role of poly (dA∶dT) tracts in stage-specific regulation of GBP130 remains unclear.

Key words: Plasmodium falciparum, transfection, glycophorin binding protein 130(GBP130), gene regulation