indeed , using both sedimentation techniques and falling ball viscometry [ fowler et al : j cell biol 88 : 388 , 1981 ] to measure actin binding by membranes , we were able to show that chromaffin granules bind f-actin via a protein site on the membrane , and that these interactions are reversibly inhibited by raising the free calcium ion concentration to micromolar levels ( [ ca++ ] free for half-maximal inhibition approximately 2.6 x 10 ( -7 ) m ) [ fowler and pollard : nature 295:336 , 1982 ] .
C0007634
cell
C1180307
f-actin