kinesin

Kinesins are a large superfamily of ATP-dependent motor proteins that move along microtubules to transport cellular cargo such as vesicles, organelles, and protein complexes, and to contribute to spindle dynamics during cell division. They are essential for intracellular logistics in most eukaryotic cells.

Most kinesins are dimers with two motor domains that bind and hydrolyze ATP, a coiled-coil stalk, and a tail that mediates cargo binding. In conventional kinesin-1, the motor domains sit at the front of the molecule and move in a hand-over-hand fashion toward the microtubule plus end, driven by cycles of ATP binding, hydrolysis, and product release. The neck linker region docks to propel the partner head forward, enabling processive movement along the microtubule. While the majority of kinesins move toward the microtubule plus end, some family members travel toward the minus end, and others regulate microtubule dynamics rather than translocate cargos.

Kinesin families perform diverse cellular tasks. Kinesin-1 transports membranous organelles and cargoes in neurons and other cell types. Kinesin-2 and kinesin-3 participate in organelle trafficking and synaptic functions. Kinesin-5 and related motors generate forces that separate and organize chromosomes during mitosis to establish spindle bipolarity, while kinesin-13 family members depolymerize microtubules to regulate dynamics. Cargo binding is often mediated by light chains and adaptor proteins, and motor activity can be controlled by autoinhibition and post-translational modifications.

Discovery and nomenclature trace to the 1980s; kinesins are conserved across eukaryotes. Clinically and in research, kinesins are attractive targets for therapies and are studied via structural techniques to reveal stepping mechanisms and conformational states.