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#myosin V

2 public questions tagged with this topic.

Cytoskeleton

What is the approximate step size of Myosin V during intracellular transport?

Myosin V stride size uniquely adapted to actin filament helical symmetry enabling straight long distance walks without spiraling around filament axis. The molecule possesses six IQ motifs per heavy chain creating extended lever about 24 nm much longer than myosin II lever. During processive movement heads alternate hand over hand trailing head detaches after ATP binding swings forward as lever rotates about 100 degrees. Actin filament repeats every 13 monomers corresponding to 36 nm axial distance where binding site orientation repeats facing same direction. Center of mass therefore advances 3

Ref: Mehta et al., Nature 1999; Purcell et al., PNAS 2005 – Myosin V 36 nm center and 72 nm head step mechanism.

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Cytoskeleton

What is the role of Myosin V in intracellular transport?

Myosin V is prototypical class V unconventional myosin that operates on actin filaments not microtubules serving local delivery after long range microtubule transport. The molecule is dimeric with two motor heads each containing six calmodulin or essential light chain IQ motifs forming a 24 nm lever arm, a coiled coil stalk and a globular tail domain that binds cargo adaptors such as Rab11, Rab27, melanophilin and Myo4p binding proteins. It moves processively hand over hand toward barbed plus end near plasma membrane hydrolyzing one ATP per step with coordinated gating that prevents simultaneo

Ref: Vale, Cell 2003; Hammer & Sellers, Nat Rev Mol Cell Biol 2012 – Myosin V processive transport on actin filaments.

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