Folia Biologica
Journal of Cellular and Molecular Biology, Charles University 

Kinesin belongs to the group of motor proteins known to convert chemical energy released from ATP into mechanical energy. It is a microtuble-associated molecular motor whose ATPase activity is strongly promoted by microtubules. Within the last decade numerous kinesin isoforms and related proteins sharing a common motor domain were described in eukaryotic organisms (Hirokawa, 1998). One prominent member of the kinesin superfamily comprising more than 100 proteins is the conventional kinesin, which essentially contributes to the anterograde vesicle transport in neuronal cells (Schnapp et al., 1992). Conventional kinesin purified from mammalian brain homogenates is a heterotetramer consisting of two heavy (120 to 130 kDa) and two light chains (60 to 70 kDa), resulting in a molecular mass about 400 kDa. Each heavy chain contains an N-terminal globular motor domain with both a microtubule-binding site and an ATPase active centre, a stalk region which is responsi ble for heavy chain dimerization, as well as a C-terminal globular tail domain which is implicated in cargo binding. Light chains seem to have a regulatory function (Verhey et al., 1998). In immunofluorescence kinesin appears to be localized on vesicles, but anti-kinesin antibodies differing in their epitope specificity label various cellular components (Lin et al., 1996). It was shown that kinesin was also involved in the interaction of microtubules with intermediate filaments of the vimentin type (Kreitzer et al., 1999).

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