Fig. 2. Molecular cloning of TCL1. (A) Diagram illustrating the insertion site of the activation-tagged T-DNA in the tcl1-1D/gpa1-2 mutant. The orientation of the four 35S-enhancer repeats in the T-DNA situated 2115 bp upstream of the start codon of TCL1 (At2g30432) is indicated by arrows. (B) RT-PCR indicating transcript level of TCL1 in wild-type, gpa1-2 and tcl1-1D/gpa1-2 Arabidopsis plants. RNA was isolated from 10-day-old light-grown seedlings. ACTIN2 provided a control. (C) The TCL1 protein is similar to other single-repeat R3 MYB transcription factors TRY, CPC, ETC1, ETC2 and At4g01060. Identical amino acids are shaded in black, similar amino acids in gray. The amino acid signature [D/E]Lx2[R/K]x3Lx6Lx3R (Zimmermann et al., 2004) that is required for interacting with R/B-like bHLH transcription factors is indicated by arrowheads. Asterisks indicate the amino acids within the MYB domain that are crucial for cell-to-cell movement (Kurata et al., 2005). (D) Phylogenetic analysis of TCL1, TRY, CPC, ETC1, ETC2 and At4g01060.