Alignment of ZF domains of family C1 and classification of the four subclasses into different subgroups. (a) C1-1iA-I including the conserved C-terminal R/K-rich ZF flank. (b) C1-2iA-D, X1, also shown are positions C-terminal (Ct) of the ZF. (c) C1-3iA-D, C1-4iA, B, only the helical sequence parts are shown. Signatures and other important positions are highlighted in yellow. The plant specific sequence QALGGH in helix (h) position 2–7 is invariant in all ZF domains except for K2-1 and K2-2 where the K/R is highlighted in pink.