The organization of individual actin filaments into higher-order
structures is controlled by actin-binding proteins (ABPs). Although
the biological significance of the ABPs is well documented, little is
known about how bundling and cross-linking quantitatively affect
the microstructure and mechanical properties of actin networks.
Here we quantify the effect of the ABP scruin on actin networks by
using imaging techniques, cosedimentation assays, multiparticle
tracking, and bulk rheology. We show how the structure of the
actin network is modified as the scruin concentration is varied, and
we correlate these structural changes to variations in the resultant
network elasticity.