Question

there is a myosin that has evolved to travel in the reverse direction towards the minus end. describe using diagrams the molecular features and dimensions that led to this direction reversal.

Answer 1

Answer:- The three major myosin proteins are organized into head, neck, and tail domains, which carry out different functions. The head domain binds actin and has ATPase activity. The neck domain can also serve as a binding site for myosin light chains which are distinct proteins that form part of a macromolecular complex and generally have regulatory functions. The tail domain generally mediates interaction with cargo molecules and/or other myosin subunits.The myosin molecule is asymmetric, having a long tail and two globular heads. It has two 220 kD heavy chains which make the majority of the overall structure and two pairs of light chains which vary in size.It has six subunits.

Myosin VI is the only member of the myosin family that moves toward the minus end of actin filaments, because of a break in the conserved sequence of its motor domain. The diversity of directional movement and tail domains allows for different cargo to be moved throughout the cell cytoplasm on actin tracks.

Myosin 6 is a reverse-direction motor protein that moves towards the minus-end of actin filaments.It has slow rate of actin-activated ADP release due to weak ATP binding. Functions in a variety of intracellular processes such as vesicular membrane trafficking and cell migration.it is required for the structural integrity of the Golgi apparatus via the p53-dependent pro-survival pathway.May play a role in transporting DAB2 from the plasma membrane to specific cellular targets

Required for structural integrity of inner ear hair cells.It modulates RNA polymerase II-dependent transcription.The minus end of an actin filament is the end that does not preferentially add actin monomers.Catalysis of movement along a microfilament towards the minus end, coupled to the hydrolysis of a nucleoside triphosphate

Reversal of directionality by repositioning the myosin lever arm.Myosin VI is an exception to this generality as it has two unique insertions in the motor domain: Insert 1 alters ATP binding under load, and insert 2 reverses the directionality of the motor.This makes myosin VI the only myosin known to move toward the pointed end of the actin filament .

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