Introduction
Kinesin 1 (herein referred to as kinesin) transports intracellular cargoes, such as membrane organelles, mRNAs, and protein complexes, along microtubules (Vale, 2003). Kinesin advances along its track in a remarkably precise manner. Each ATP binding/hydrolysis cycle causes kinesin to take an 8 nm step (Svoboda et al., 1993), the distance between adjacent α/β tubulin dimers along the long axis of the microtubule. At low loads, these steps are virtually always directed along a single protofilament track toward the microtubule plus end (Carter and Cross, 2005 and Ray et al., 1993).