Microtubule-dependent motor protein involved in the control of the oriented deposition of cellulose microfibrils (PubMed:20444225, PubMed:21325138). Involved in wall biogenesis and modification, and contributes to cell-cycle progression and cell division (PubMed:20444225). Acts as a transcriptional activator in gibberellic acid (GA) biosynthesis pathway. Binds specifically to the DNA sequence 5'-ACCAACTTGAA-3' of the ent-kaurene oxidase 2 (CYP701A6 or OsKO2) promoter. May regulate CYP701A6 gene expression and mediates cell elongation by regulating the GA biosynthesis pathway (PubMed:21325138). May be regulated by cyclin-dependent kinase A. Homodimer. Associated with mitotic microtubule arrays during cell division. Expressed in young tissues with cell divisions, including initiating adventitious roots, primary root tips, flower primordia, intercalary meristems, sub-epidermal regions of young culms and panicles. Composed of an N-terminal domain which is responsible for the motor activity of kinesin (it hydrolyzes ATP and binds microtubule) and a central to C-terminal alpha-helical coiled coil domain that mediates the heavy chain dimerization. Dwarf plants due to significant reduction in cell number (PubMed:20444225). Dwarf plants due to significant reduction in cell elongation (PubMed:21325138). This phenotype can be rescued by exogenous gibberellic acid (GA3) treatment (PubMed:21325138). Reduced mechanical strength (brittleness) due to an alteration in cellulose microfibril orientation and wall composition (PubMed:20444225). Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Kinesin family. KIN-4 subfamily.