— intracellular protein, belonging to the class of molecular motors and transporting organelles, vesicles and protein complexes along microtubules - components of the cell skeleton (cytoskeleton).
A kinesin molecule consists of two heavy chains whose molecular weight is ca. 120 kDa (thousand atomic mass units), and two light chains whose weight is 64 kDa. Heavy chains form globular motor domains at one end of the molecule, then they are twisted together to form a dimeric so-called coiled-coil domain. The opposite end of the kinesin molecule is formed by two light chains and is involved in the binding of cargo (vesicles, mitochondria). There are more than 14 known families of kinesin molecular motors. They mainly carry out transport from the centre of the cell
in the direction of the cytoplasmic membrane
. Motors which transport cargos along microtubules in the opposite direction belong to the family of dyneins. Kinesins, dyneins and other motor proteins use adenosine triphosphate (ATP) molecules as their energy source.
Kinesin molecule structure.