Dynamic Properties of Motor Proteins with Two Subunits

TL;DR

This paper models the dynamics of two-subunit motor proteins, deriving exact analytical expressions for their movement and comparing two mechanisms, providing insights into their speed, fluctuations, and how to distinguish between mechanisms experimentally.

Contribution

It introduces exact steady-state analytical models for two-subunit motor proteins and compares hand-over-hand and inchworm mechanisms, proposing a method to distinguish them experimentally.

Findings

Hand-over-hand mechanism results in faster movement.

Particles in the hand-over-hand mechanism fluctuate more.

External forces influence motor protein dynamics.

Abstract

The dynamics of motor protein molecules that have two subunits is investigated using simple discrete stochastic models. Exact steady-state analytical expressions are obtained for velocities and dispersions for any number of intermediate states and conformations between the corresponding binding states of proteins. These models enabled a detailed description and comparison of two possible mechanisms of the motion of motor proteins along the linear tracks: the hand-over-hand mechanism when the motion of subunits alternate, and the inchworm mechanism when one subunit is always trailing another one. It is shown that particles in the hand-over-hand mechanism move faster and fluctuate more than the molecules in the inchworm mechanism. The effect of external forces on dynamic properties of motor proteins is discussed. Finally, a method is proposed for distinguishing between these two mechanisms based on experimental observations.