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Tropomodulins are a family of important regulators of actin dynamics at the pointed ends of actin filaments. Four isoforms of tropomodulin, Tmod1‐Tmod4, are expressed in vertebrates. Binding of tropomodulin to the pointed end is dependent on tropomyosin, an actin binding protein that itself is represented in mammals by up to 40 isoforms. The understanding of the regulatory role of the tropomodulin/tropomyosin molecular diversity has been limited due to the lack of a three‐dimensional structure of the tropomodulin/tropomyosin complex. In this study, we mapped tropomyosin residues interacting with two tropomyosin‐binding sites of tropomodulin and generated a three‐dimensional model of the tropomodulin/tropomyosin complex for each of these sites. The models were refined by molecular dynamics simulations and validated via building a self‐consistent three‐dimensional model of tropomodulin assembly at the pointed end. The model of the pointed‐end Tmod assembly offers new insights in how Tmod binding ensures tight control over the pointed end dynamics.

A novel method of protein encapsulation is proposed. Preformed protein aggregates are covered with polyelectrolyte layers by means of layer-by-layer adsorption. The polyelectrolyte membrane prevents protein leakage out of the capsule. Using chymotrypsin as a model enzyme the capsule wall selective permeability was demonstrated for substrates and inhibitors of different molecular weight and solubility.