Binds to the CACCC box of erythroid cell-expressed genes. May play a role in hematopoiesis. Monomer. In 8.5 day embryos, expressed in midbrain, anterior hindbrain and ventral forebrain. In 9 day embryos, expressed throughout ventral anterior half of embryo including midbrain-hindbrain junction, ventral midbrain, diencephalon and forebrain. At 10.5 days, distribution is more widespread with expression also found in developing limb buds. Widely expressed in the adult. 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-197 is the major site. Belongs to the krueppel C2H2-type zinc-finger protein family.