Fig. 1. (A) The delineated functional and structural domains in calponins. Primary domains are the CH domain, the strong actin-binding site (ABS1), the adjacent triple CLIK repeats harboring the ABS2, and the C-terminal tail. (B) Amino acid exchanges in h2 CaP within the ABS1 region at positions 151 and 156. Note the characteristic h2-type exchanges in the ABS1 region of XCaPH3 from Xenopus laevis. (C) CaP mutants used in this study. All constructs carry the GFP fusion at their respective N-terminal ends. Color coding refers to h1 CaP (pink), h2 CaP (orange), and acidic CaP (brown). The non-functional ABS1 in h2 CaP is shown in gray. Mutant domains are shown as hatched blue boxes.