Transactivator required for FRIGIDA-mediated activation of FLC and for the expression of the repressors of flowering AGL27/MAF1 and AGL31/MAF2. Does not alter expression of known activators of FLC expression. Not required for the photoperiod response or for the vernalization response. Not redundant with FLXL4. Homodimer. Component of the transcription activator complex FRI-C composed of FRI, FRL1, SUF4, FLX and FES1. Interacts with FES1 and (via N-terminus) with FRI (via C-terminus). Interacts with SWC6, TAF14B and RIN1, three components of the SWR1 chromatin-remodeling complex. homodimers present in the cytosol and heterodimers with FRI and FES1 detected only in the nucleus. Expressed in roots and leaves. Expressed in shoot and root apical meristems and vascular tissues. Early flowering. Decreased level of H3K4me3 and histone H3 and H4 acetylation in the region spanning the transcription-translation start site of FLC, but not of UFC or DFC. Belongs to the FLX family.