25.11 : Actin Polymerization
Actin polymerization occurs through the head-to-tail association of binding sites on monomeric actin or G-actin to form filamentous or F-actin. The polymerization can be divided into three phases ̶ nucleation, elongation, and steady-state phase.
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin filaments with the help of actin-profilin complexes. They can form clusters near the plasma membrane to initiate actin filament formation. While in the cytoplasm, they may participate in the elongation phase of pre-existing actin filaments. During elongation of actin filaments, formins remove the capping proteins and form a sleeve around the actin subunits. The removal of capping proteins involves the dimerization of formin in the shape of a donut and binding to a pre-existing filament through the formin homology 2 or FH2 domain. Additionally, the FH1 domains of formin monomers also capture the profilin-G-actin complexes, thereby promoting the addition of G-actin to the filament.
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25.11 : Actin Polymerization
The Cytoskeleton I: Actin and Microfilaments
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25.1 : Introduction to the Cytoskeleton
The Cytoskeleton I: Actin and Microfilaments
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25.2 : Adaptability of Cytoskeletal Filaments
The Cytoskeleton I: Actin and Microfilaments
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25.3 : Polarity of the Cytoskeleton
The Cytoskeleton I: Actin and Microfilaments
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25.4 : Assembly of Cytoskeletal Filaments
The Cytoskeleton I: Actin and Microfilaments
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25.5 : Cytoskeletal Linker Proteins - Plakins
The Cytoskeleton I: Actin and Microfilaments
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25.6 : Cytoskeletal Accessory Proteins
The Cytoskeleton I: Actin and Microfilaments
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25.7 : Cytoskeletal Proteins in Bacteria
The Cytoskeleton I: Actin and Microfilaments
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25.8 : Intracellular Movement of Viruses and Bacteria
The Cytoskeleton I: Actin and Microfilaments
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25.9 : Studying the Cytoskeleton
The Cytoskeleton I: Actin and Microfilaments
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25.10 : Introduction to Actin
The Cytoskeleton I: Actin and Microfilaments
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25.12 : Actin Treadmilling
The Cytoskeleton I: Actin and Microfilaments
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25.13 : Generation of Straight or Branched Actin Filaments
The Cytoskeleton I: Actin and Microfilaments
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25.14 : Actin Filament Depolymerization
The Cytoskeleton I: Actin and Microfilaments
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25.15 : Formation of Higher-order Actin Filaments
The Cytoskeleton I: Actin and Microfilaments
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