Motorproteïnen

Motorproteïnen are a class of globular proteins that convert chemical energy derived from adenosine triphosphate (ATP) into mechanical force, enabling transport and movement within cells. They are essential for a wide variety of cellular processes, including vesicle trafficking, organelle positioning, chromosome segregation during cell division, and muscle contraction in multicellular organisms.

Structurally, motorproteïnen possess a motor domain that binds and hydrolyzes ATP, a lever arm that amplifies the resulting conformational changes, and cargo‑binding sites that attach to microtubules, actin filaments, or other cellular structures. The binding and hydrolysis cycle of ATP induces a series of coordinated shape changes that allow the protein to “walk” along its filamentous track.

The most studied motorproteïnen families are kinesins, dyneins, and myosins. Kinesins move predominantly toward the plus end of microtubules and are primarily involved in anterograde intracellular transport. Cytoplasmic dyneins travel toward the minus end of microtubules, directing retrograde transport and playing a key role in spindle assembly. Myosins interact with actin filaments, mediating muscle contraction, cell motility, and intracellular cargo movement. Within each family, numerous isoforms exist, showing specialization for tissue type, developmental stage, or subcellular localization.

Defects or mutations in motorproteïnen disrupt cellular function and are implicated in a variety of human disorders, such as neurodegenerative diseases, muscular dystrophies, and congenital motor neuropathies. Accordingly, understanding the detailed mechanisms of motorprotein function remains a major focus of cell biology and medical research.