The region in a subunit of the Aspergillus CCAAT-binding protein similar to the HAP4p-recruiting domain of Saccharomyces cerevisiae Hap5p is not essential for transcriptional enhancement.

The CCAAT-binding complex in Aspergillus species, known as the Hap complex, consists of at least three subunits, HapB, HapC, and HapE. Each Hap subunit contains an evolutionarily conserved core domain. In this study, a series of the truncated gene, which encodes the HapE subunit of Aspergillus oryzae, was constructed to survey the regions essential for the transcriptional enhancement of fungal genes. It was revealed that the non-conserved regions and the conserved region similar to the Hap4p recruiting domain of Saccharomyces cerevisiae were not necessary for Hap complex-mediated transcriptional enhancement.