Fig 1.

ZFP-1 contains two N-terminal PHD fingers that are highly conserved. (A) Diagram of the zfp-1 gene locus showing its two predicted isoforms, the ok554 deletion, and the region targeted in RNAi experiments. (B) The 867-aa ZFP-1 protein has two predicted plant homeodomains (PHDs) in the N terminus (aa 1 to 189) and an octapeptide motif and leucine zipper (OM and LZ; aa 594 to 655) in the C terminus. The short isoform protein is missing the N-terminal PHD fingers but retains the OM and LZ in the C terminus. In the mRNA of the ok554 mutant, exon 4 becomes spliced to exon 7 (see panel A), and this leads to expression of a truncated version of the long isoform which retains the first 4 exons (amino acids 1 to 190) followed by a frameshift that expresses an additional 49-amino-acid fragment out of frame and results in a premature stop codon. (C) Primary sequence alignment of the PHD1-PHD2 region of C. elegans ZFP-1 with homologs in four other species, as indicated. Asterisks indicate the cysteine and histidine residues that are predicted to coordinate zinc ions. The blue box indicates the peptide used to raise an N terminus-specific antibody to ZFP-1.