Figure 1.

Mutations designed to cover all residues involved with binding various ligands, e.g., the binding with actin (a), poly-l-proline (p), and PIP₂ (+), marked on top of the wild-type S. pombe profilin sequence. Some residues may participate in both actin and PIP₂ binding. Each point mutant is represented by the mutated amino acid that aligns with the wild-type sequence. E42K (*) is the mutation of profilin in cdc3-124 ts strain. C89S (*) is a control mutant for structure stability. Mutants that failed to complement both null (32°C) and ts (36°C) strains are bold and underlined; mutants that complemented the ts at 36°C but not the null strain at 32°C are bold only. Four of these noncomplementing mutants complement null strain at 25°C (i).