ACTC1 encodes cardiac muscle alpha actin.[5][6] This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle contraction and generation of force to support the pump function of the heart.
Cardiac alpha actin is a 42.0 kDa protein composed of 377 amino acids.[7][8] Cardiac alpha actin is a filamentous protein extending from a complex mesh with cardiac alpha-actinin (ACTN2) at Z-lines towards the center of the sarcomere. Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each actin can bind to four others. The atomic structure of monomeric actin was solved by Kabsch et al.,[9] and closely thereafter this same group published the structure of the actin filament.[10] Actins are highly conserved proteins; the alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. Cardiac (ACTC1) and skeletal (ACTA1) alpha actins differ by only four amino acids (Asp4Glu, Glu5Asp, Leu301Met, Ser360Thr; cardiac/skeletal). The actin monomer has two asymmetric domains; the larger inner domain comprised by sub-domains 3 and 4, and the smaller outer domain by sub-domains 1 and 2. Both the amino and carboxy-termini lie in sub-domain 1 of the outer domain.
Actin is a dynamic structure that can adapt two states of flexibility, with the greatest difference between the states occurring as a result of movement within sub-domain 2.[11] Myosin binding increases the flexibility of actin,[12] and cross-linking studies have shown that myosin subfragment-1 binds to actin amino acid residues 48-67 within actin sub-domain 2, which may account for this effect.[13]
It has been suggested that the ACTC1 gene has a role during development. Experiments in chick embryos found an association between ACTC1 knockdown and a reduction in the atrial septa.[14]
Polymorphisms in ACTC1 have been linked to dilated cardiomyopathy in a small number of Japanese patients.[15] Further studies in patients from South Africa found no association.[16] The E101K missense mutation has been associated with hypertrophic cardiomyopathy[17][18][19][20] and left ventricular noncompaction.[21] Another mutation has in the ACTC1 gene has been associated with atrial septal defects.[14]
PDB gallery
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1atn: Atomic structure of the actin:DNASE I complex
1c0g: CRYSTAL STRUCTURE OF 1:1 COMPLEX BETWEEN GELSOLIN SEGMENT 1 AND A DICTYOSTELIUM/TETRAHYMENA CHIMERA ACTIN (MUTANT 228: Q228K/T229A/A230Y/E360H)
1d4x: Crystal Structure of Caenorhabditis Elegans Mg-ATP Actin Complexed with Human Gelsolin Segment 1 at 1.75 A resolution.
1dej: CRYSTAL STRUCTURE OF A DICTYOSTELIUM/TETRAHYMENA CHIMERA ACTIN (MUTANT 646: Q228K/T229A/A230Y/A231K/S232E/E360H) IN COMPLEX WITH HUMAN GELSOLIN SEGMENT 1
1eqy: COMPLEX BETWEEN RABBIT MUSCLE ALPHA-ACTIN: HUMAN GELSOLIN DOMAIN 1
1esv: COMPLEX BETWEEN LATRUNCULIN A:RABBIT MUSCLE ALPHA ACTIN:HUMAN GELSOLIN DOMAIN 1
1h1v: GELSOLIN G4-G6/ACTIN COMPLEX
1hlu: STRUCTURE OF BOVINE BETA-ACTIN-PROFILIN COMPLEX WITH ACTIN BOUND ATP PHOSPHATES SOLVENT ACCESSIBLE
1ijj: THE X-RAY CRYSTAL STRUCTURE OF THE COMPLEX BETWEEN RABBIT SKELETAL MUSCLE ACTIN AND LATRUNCULIN A AT 2.85 A RESOLUTION
1j6z: UNCOMPLEXED ACTIN
1kxp: CRYSTAL STRUCTURE OF HUMAN VITAMIN D-BINDING PROTEIN IN COMPLEX WITH SKELETAL ACTIN
1lcu: Polylysine Induces an Antiparallel Actin Dimer that Nucleates Filament Assembly: Crystal Structure at 3.5 A Resolution
1lot: CRYSTAL STRUCTURE OF THE COMPLEX OF ACTIN WITH VITAMIN D-BINDING PROTEIN
1m8q: Molecular Models of Averaged Rigor Crossbridges from Tomograms of Insect Flight Muscle
1ma9: Crystal structure of the complex of human vitamin D binding protein and rabbit muscle actin
1mdu: Crystal structure of the chicken actin trimer complexed with human gelsolin segment 1 (GS-1)
1mvw: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1nlv: Crystal Structure Of Dictyostelium Discoideum Actin Complexed With Ca ATP And Human Gelsolin Segment 1
1nm1: Crystal Structure of D. Dicsoideum Actin Complexed With Gelsolin Segment 1 and Mg ATP at 1.8 A Resolution
1nmd: Crystal Structure of D. Discoideum Actin-Gelsolin Segment 1 Complex Crystallized In Presence Of Lithium ATP
1nwk: CRYSTAL STRUCTURE OF MONOMERIC ACTIN IN THE ATP STATE
1o18: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o19: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1a: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1b: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1c: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1d: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1e: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1f: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1o1g: MOLECULAR MODELS OF AVERAGED RIGOR CROSSBRIDGES FROM TOMOGRAMS OF INSECT FLIGHT MUSCLE
1p8z: Complex Between Rabbit Muscle alpha-Actin: Human Gelsolin Residues Val26-Glu156
1qz5: Structure of rabbit actin in complex with kabiramide C
1qz6: Structure of rabbit actin in complex with jaspisamide A
1rdw: Actin Crystal Dynamics: Structural Implications for F-actin Nucleation, Polymerization and Branching Mediated by the Anti-parallel Dimer
1rfq: Actin Crystal Dynamics: Structural Implications for F-actin Nucleation, Polymerization and Branching Mediated by the Anti-parallel Dimer
1rgi: Crystal structure of gelsolin domains G1-G3 bound to actin
1s22: Absolute Stereochemistry of Ulapualide A
1sqk: CRYSTAL STRUCTURE OF CIBOULOT IN COMPLEX WITH SKELETAL ACTIN
1t44: Structural basis of actin sequestration by thymosin-B4: Implications for arp2/3 activation
1wua: The structure of Aplyronine A-actin complex
1y64: Bni1p Formin Homology 2 Domain complexed with ATP-actin
1yxq: Crystal structure of actin in complex with swinholide A
2a3z: Ternary complex of the WH2 domain of WASP with Actin-DNAse I
2a40: Ternary complex of the WH2 domain of WAVE with Actin-DNAse I
2a41: Ternary complex of the WH2 Domain of WIP with Actin-DNAse I
2a42: Actin-DNAse I Complex
2a5x: Crystal Structure of a Cross-linked Actin Dimer
2asm: Structure of Rabbit Actin In Complex With Reidispongiolide A
2aso: Structure of Rabbit Actin In Complex With Sphinxolide B
2asp: Structure of Rabbit Actin In Complex With Reidispongiolide C
2btf: THE STRUCTURE OF CRYSTALLINE PROFILIN-BETA-ACTIN
2d1k: Ternary complex of the WH2 domain of mim with actin-dnase I
2ff3: Crystal structure of Gelsolin domain 1:N-wasp V2 motif hybrid in complex with actin
2ff6: Crystal structure of Gelsolin domain 1:ciboulot domain 2 hybrid in complex with actin
2fxu: X-ray Structure of Bistramide A- Actin Complex at 1.35 A resolution.
2gwj: SpvB ADP-ribosylated actin: hexagonal crystal form
2gwk: SpvB ADP-ribosylated actin: orthorhombic crystal form
2hf3: Crystal structure of monomeric Actin in the ADP bound state
2hf4: Crystal structure of Monomeric Actin in its ATP-bound state
2hmp: Uncomplexed actin cleaved with protease ECP32
2oan: Structure of oxidized beta-actin
2q1n: Actin Dimer Cross-linked Between Residues 41 and 374
2q31: Actin Dimer Cross-linked Between Residues 41 and 374 and proteolytically cleaved by subtilisin between residues 47 and 48.
2q36: Actin Dimer Cross-linked between Residues 191 and 374 and complexed with Kabiramide C
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Proteins of the cytoskeleton
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See also: cytoskeletal defects |