Component of the kinesin II motor complex (composed of kap-1 and the heterodimeric motor proteins klp-11 and klp-20) which is required for intraflagellar transport (IFT) (PubMed:20833139, PubMed:20498083). Heterodimerizes with klp-11 to form a 'processive' molecular motor upon IFT cargo binding, which, within the kinesin II motor complex, binds to and moves along microtubules in a unidirectional manner (without dissociation of the heterodimer), and in turn, is responsible for the IFT of cargo (PubMed:20498083). Specifically, the kinesin II motor complex, together with the kinesin motor protein osm-3 moves along microtubules and is required for anterograde IFT along the middle segment of the sensory neuron cilia (PubMed:17000880, PubMed:20833139, PubMed:28479320). In particular, the kinesin II motor complex delivers specific ciliary cargo proteins such as che-3 which are related to motility to ciliary tips (PubMed:28479320). This is likely mediated by IFT complexes A and B (PubMed:28479320). Component of the kinesin II motor complex, a heterotrimeric complex composed of kap-1, klp-11 and klp-20 (PubMed:17000880, PubMed:20833139, PubMed:20498083, PubMed:28479320). Interacts (via C-terminus) with klp-11 (via C-terminus) to form a heterodimer (PubMed:20498083, PubMed:21917588). Furthermore, within the heterodimer, the C-termini of klp-20 and klp-11 interact to form a coiled coil (stalk) or tail domain, and this is necessary for association with kap-1, and kinesin II motor complex activity upon IFT cargo binding (PubMed:20498083, PubMed:21917588). Prior to cargo binding, the klp-11/klp-20 heterodimer is autoinhibited by the tail domain of the heterodimer, which folds onto the kinesin motor domain (PubMed:20498083). Cargo binding to the heterodimer relieves the autoinhibition, and allows for an extended conformation of the tail domain, and function of the heterodimer (PubMed:20498083). In particular, localizes to the base and transition zone of cilia. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Kinesin family. Kinesin II subfamily.