Binds to actin filaments and promotes cross-linking into thick bundles. Has an actin-stabilizing activity. The actin regulatory activities are inhibited by pH > 6.8 but are [Ca(2+)] independent. Interacts with F-actin. Predominantly expressed in flowers, in the tapetum and in pollen grains. Detected in leaves and stems. Cross-links actin with a constant of dissociation of 1.3 uM.