Recombinant ABP29 and ABP135_G1-G3 fusion proteins sever and/or depolymerize actin filaments in a calcium-dependent manner.

<p>(A) Domain structures of gelsolin superfamily members studied in the paper. The lily ABP135,with six G domains and a headpiece (HP) domain at the C-terminus, is designated as ABP135. Full-length human gelsolin, containing six G-domains, is designated as Gelsolin. ABP135_G1-G3 containing the G1-G3 domains is part of ABP135. <i>Lilium</i> ABP29 is a splicing product of ABP135, and the small black dot at the end of ABP29 represents the six amino acids that differ from ABP135. ABP29-△C6 has six fewer amino acids than ABP29 at the C-terminus. ABP29_G1-G2 contains only the G1-G2 domains of ABP29. (B) SDS-PAGE analysis of purified recombinant ABP29 and ABP135_G1-G3. Molecular mass markers (M) in kiloDaltons are shown to the left of the gel. (C) Detailed comparison of ABP29 and ABP135_G1-G3 severing and/or depolymerization activities in the presence of different concentrations of Ca²⁺ with high-speed co-sedimentation assays; "(s)" indicates supernatant, "(p)" indicates pellets, and "ABP" indicates ABP29 or ABP135_G1-G3. (D-F) Statistical analysis results from (C). The graph shows the percentage of actin in the supernatant. The concentrations of the recombinant proteins are 0.3, 0.6 and 1.0 μM, respectively in (D-F). The CK is the percentage of actin in the supernatant in the absence of ABP. The error bars represent ± SE (n = 3); *P < 0.05 (Student’s <i>t</i> test).