Binds to the CACCC box of erythroid cell-expressed genes. May play a role in hematopoiesis (By similarity). Monomer. The 9aaTAD motif is a transactivation domain present in a large number of yeast and animal transcription factors. In KLF3, the motif is inactive. Sumoylated with SUMO1. Sumoylation is enhanced by PIAS1, PIAS2alpha and PIAS2beta, and PIAS4, but not by Pc2. Enhances transcriptional repression, but has no effect on DNA binding. Sumoylation on Lys-198 is the major site (By similarity). May be due to intron retention. Belongs to the krueppel C2H2-type zinc-finger protein family.