Figure 3.

Predicted amino acid sequence of the Arabidopsis SCA3 protein (RpoTp; Y08463). Residues shaded in black are identical across the sequences of homologous gene products from H. vulgare (CAD45446), T. aestivum (AF091839), Z. mays (AF127022), O. sativa (AB120430), N. sylvestris (AJ302020), and tobacco (AJ416570). Residues with similar chemical properties conserved across all seven sequences are shaded gray. The alignment was obtained using ClustalX, version 1.5b. Continuous and dotted thin lines indicate the domains (I–XI) and the C-motif that are conserved among T7 phage-type NEP plastid RNAPs, respectively (McAllister and Raskin, 1993; Chang et al., 1999). The amino acid sequences deleted in the mutant protein products of sca3-1b (see Fig. 2), sca3-2, and sca3-3 are indicated by white boxes, thick discontinuous lines, and black boxes, respectively.