Actin binding proteins

Actin binding proteins - actin filaments closely together...

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Actin binding proteins thymosin - is the most abundant actin binding protein Its role is to sequester actin monomers preventing them from being assembled into filaments. profilin - has the same activity. However, it can promote monomer incorporation into filaments by stimulating the exchange of bound ADP for ATP. capping proteins - bind to the ends of actin filaments and prevent the loss or addition of actin monomers. - Organization of Actin Filaments actin filaments rarely occur in isolation in the cell, generally found in: actin bundles filaments are cross-linked into closely packed parallel arrays actin networks filaments are loosely cross-linked in orthogonal arrays that form a 3D meshwork with the properties of semisolid gels. Actin Bundling Proteins fimbrin - has 2 adjacent actin-binding domains allowing it to hold 2 parallel
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Unformatted text preview: actin filaments closely together. • a-actinin serves as a cross-linking protein and binds to actin as a dimer. Because it is a dimer, the filaments are `40nm apart as opposed to 14nm apart. The increased space allows the motor protein myosin to interact with the actin filaments- enabling them to contract. • ACTIN NETWORKS Actin networks are held together by large actin binding proteins such as filamin • Filamin binds as a dimer of 2 (280kda) subunits. • It is a flexible V-shaped molecule with actin-binding domains at the ends of both arms. When it is bound it forms cross-links between orthogonal actin filaments. This network underlies the plasma membrane and supports the surface of cells....
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