IKAROS Family Zinc Finger Protein 5 (IKZF5)

Pegasus has a conserved C-terminal zinc finger cluster. Pegasus has little homology in its other regions to Ikaros family proteins, and it has 3 divergent N-terminal zinc fingers rather than the 4 N-terminal fingers conserved in the other members. GST pull-down experiments showed that the C-terminal zinc fingers of Pegasus interact with other Ikaros proteins and with Pegasus itself, establishing the presence of functional dimerization domains. DNA binding analysis indicated that Eos, but not Pegasus, interacts with high affinity with sequences similar to those bound by Ikaros and other family members. Pegasus was found to preferentially recognize GnnTGTnG rather than the tGGGAatacc site recognized by other Ikaros family members. Reporter analysis demonstrated that Pegasus acts as a transcriptional repressor at its sites but not at Eos sites.