Transcription factor which promotes the expression of heat stress-inducible genes by contributing to the formation of a heat stress-specific transcriptional complex with NF-Y subunits (e.g. NF-YA2 and NF-YB3) and DREB2A at the promoter of target genes, thus promoting heat tolerance. Together with the glyceraldehyde-3-phosphate dehydrogenase (GAPC), enhances heat tolerance