Brevin, a serum protein that acts on the barbed end of actin filaments

It has previously been shown that brevin, a relatively abundant serum protein, inhibits salt-induced polymerization of actin and reduces the length of actin filaments in vitro. In this study, we find that in the presence of calcium, brevin inhibits actin polymerization that has been nucleated by spectrin-band 4.1-actin complex from erythrocytes. Brevin also blocks elongation of actin filaments from reconstituted inside-out erythrocyte ghosts. Thus, brevin resembles the cytochalasins in inhibiting actin filament elongation by binding to the rapidly growing end of actin filaments (the barbed end after heavy meromyosin decoration). Brevin, like gelsolin from macrophages and villin from intestinal brush border, also appears capable of severing preformed actin filaments and disrupting filament networks as measured with a low-shear falling ball viscometer.