4PKG

Complex of ATP-actin With the N-terminal Actin-Binding Domain of Tropomodulin

Summary for 4PKG

• Entry DOI: 10.2210/pdb4pkg/pdb
• Related: 4PKH 4PKI
• Descriptor: Actin, alpha skeletal muscle, Gelsolin,Tropomodulin-1 chimera, ADENOSINE-5'-TRIPHOSPHATE, ... (5 entities in total)
• Functional Keywords: tmod, actin filament, pointed-end capping protein, tropomyosin, contractile protein, actin-binding protein, contractile protein-actin-binding protein complex, contractile protein/actin-binding protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 2
• Total formula weight: 63561.79

Authors

Rao, J.N.,Dominguez, R. (deposition date: 2014-05-14, release date: 2014-07-30, Last modification date: 2023-09-27)

Primary citation

Rao, J.N.,Madasu, Y.,Dominguez, R.
Actin cytoskeleton. Mechanism of actin filament pointed-end capping by tropomodulin.
Science, 345:463-467, 2014

PubMed Abstract: Proteins that cap the ends of the actin filament are essential regulators of cytoskeleton dynamics. Whereas several proteins cap the rapidly growing barbed end, tropomodulin (Tmod) is the only protein known to cap the slowly growing pointed end. The lack of structural information severely limits our understanding of Tmod's capping mechanism. We describe crystal structures of actin complexes with the unstructured amino-terminal and the leucine-rich repeat carboxy-terminal domains of Tmod. The structures and biochemical analysis of structure-inspired mutants showed that one Tmod molecule interacts with three actin subunits at the pointed end, while also contacting two tropomyosin molecules on each side of the filament. We found that Tmod achieves high-affinity binding through several discrete low-affinity interactions, which suggests a mechanism for controlled subunit exchange at the pointed end.

PubMed: 25061212
DOI: 10.1126/science.1256159

Experimental method

X-RAY DIFFRACTION (1.8 Å)