Most plant transcriptional regulators that have been described to date belong to proteins characterized by helix-loop-helix or Leu zipper motifs. The Cys-rich sequence Cys-X2-Cys-X11-Cys-Cys-X2-Cys-X4-His-X2-Cys-X9-His-X5-Cys-X2-Cys- encoded by Alfin-1 contains one putative Cysr zinc finger structure and another His/Cyss structure, thus making it a good candidate for a new category of zinc finger nucleic acid-binding protein in plants. This region shows a very remarkable conservatjon of sequence homology with a novel Cys-rich sequence motif found in a group of diverse proteins thought to interact with DNA. The sequence encoded by Alfin-1 appears to be the first plant
member of this Cys-rich sequence family. The linker region between the two putative zinc finger motifs in Alfin-1 is four amino acids. Each of the possible zinc fingers in Alfin-1 contains predicted short alfa-helical and beta-sheet regions that are consistent with the proposed structures for zinc finger interactions with the major groove of nucleic acids.
cDNA encoding putative zinc finger motifs from salt-tolerant alfalfa (Medicago sativa L.)
Plant Physiol. 1993 June; 102 (2): 681