This is the ZF1 (Zinc Finger 1) domain found in Zic family proteins found in Eukaryotes. In humans, there are five members of the Zic family that are involved in human congenital anomalies. One of them, ZIC3, causes X-linked heterotaxy (HTX1), which is a left-right axis disturbance that manifests as variable combinations of heart malformation, altered lung lobation, splenic abnormality and gastrointestinal malrotation. Zic faily proteins contain multiple zinc finger domains (ZFD), which are generally composed of five tandemly repeated C2H2 zinc finger (ZF) motifs. Sequence comparison analysis reveal that this N-terminal ZF (ZF1) domain of the Zic zinc finger domains is unique in that it possesses more amino acid residues (6-38 amino acids) between the two cysteine residues of the C2H2 motif compared to Gli and Glis ZF1s or any of the other ZFs (ZF2-5) in the Gli/Glis/Zic superfamily of proteins. Mutations in cysteine 253 (C253S) or histidine 286 (H286R) in ZIC3 ZF1, which are found in heterotaxy patients, result in extranuclear localization of the mutant ZIC3 protein. Furthermore, mutations in the evolutionarily conserved amino acid residues (C253, W255, C268, H281 and H286) of ZF1 generally impair nuclear localization [].
