Moving on to the cargo problem of microtubule-dependent motors in neurons

Vigorous investigation has finally begun to shed light on the cargo problem of the microtubule-dependent motors, kinesin and dynein superfamily protei ns. Biochemical observations have suggested that the potential cargoes of c ertain populations of motor proteins seem to be in vesicle-form, each vesic le possessing specific functional marker molecules. In addition to the clos e relationship between microtubule-dependent motors and cargoes in vesicle- form, kinesin has also been highlighted as an apparent driving force for an other cargo in non-vesicle-form, cytoplasmic protein. On the basis of new b iophysical and cell-biological evidence, the controversy over the movement of cytoplasmic cargoes has entered a new phase.