MKLP1 requires specific domains for its dendritic targeting

The mitotic kinesin-like protein 1 (MKLP1) is specifically localized to the dendrite of the developed neuron, but its targeting mechanism is still unclear. In this study, the role of distinct domains of MKLP1 in dendritic targeting was investigated by producing a series of enhanced green fluorescent protein (eGFP)-tagged MKLP1 and its variant mutations, and studying the distribution of these molecules in cultured primary hippocampal neurons using fluorescence microscopy. We have found that: (a) full-length MKLP1(1-856)-eGFP was distributed to the dendrite of hippocampal neurons, not the axon; (b) deletion of the 'motor' domain prevented the dendritic distribution; (c) deletion of the 'tail' domain caused axonal appearance; (d) mutants devoid of the 'stalk' domain were still specifically distributed to the dendrite. The results indicate that the motor and tail regions of MKLP1 are important and significant for its localization to the dendrites. We also discuss the difference between the targeting of membrane-anchoring proteins and the kinesin-like protein.