Fig. 1.
Proteins used in this study. (A) Sequences of SPC-SH3, PI3-SH3, and the variants used in this study. Numbers correspond to the PI3-SH3 sequence. Conserved residues between SPC-SH3 and PI3-SH3 are highlighted in yellow. Data Submission Software Package and the Protein Data Bank files corresponding to PI3-SH3 (1pnj) and SPC-SH3 (1shg) were used to locate secondary structure motifs (60): β-strands appear in blue, and RT loops, diverging turns (D-T), and n-src loops appear in red, green, and purple, respectively. Highlighted in black are positions substituted in the respective mutants. (B) Three-dimensional structures of SPC-SH3 and PI3-SH3. The location of the RT loop and diverging turn is indicated in orange in both proteins, and the n-src loop is shown in magenta. The diverging turn is indicated with two green arrows in both the SPC-SH3 and PI3-SH3 structures. The fragment colored yellow in SPC-SH3 is the stretch of amino acids replaced by those of PI3-SH3 to generate the mutant SPC-PI3DT. The side chains of the residues of the RT loop and the diverging turn that were mutated in PI3-SH3 protein are colored yellow.