Fig. 2. cDNA sequence, genomic organization and nuclear localization of PTL. (A) Sequence of PTL cDNA D171 (Accession number AY555728), and the predicted amino acid sequence showing two trihelix DNA-binding domains (shaded), a conserved alpha-helical central domain (dotted line) that includes a predicted coiled-coil domain (solid line), and putative nuclear localization sequences (bold). The sites of the single intron, and of sequence changes in five ptl mutant alleles, are also shown. (The 100 bp deletion in ptl-3 is associated with the insertion of TTTTATGT at the same site.) (B) Genomic organization surrounding PTL, showing putative translated regions (green) and an intron (white). The 10.7 kb clone that fully complemented the ptl mutant phenotype is also shown (intergenic regions – yellow). Five reporter gene constructs carry the GUS gene (blue) translationally fused downstream of PTL genomic regulatory sequences, in some cases including the 1,127 bp intron (white). (C,D) Onion epidermal cells showing nuclear localization of the PTL protein translationally fused downstream of GFP (C), compared with location of control GFP protein alone (D). Left, bright field; right, GFP fluorescence of same field. Scale bars in C,D: 100 µm.