a, A kymograph for dimeric kin14-VIb motors reveals no processive movement. b, A kymograph for the GFP-kin14-VIb GCN4 tetramer construct exhibits clear processive movement (diagonal lines) and long run lengths. Movie frames show two separate GFP spots (arrows), moving along a MT (blue). c, Representative traces of the photobleaching of kin14-VIb FL and the kin14-VIb GCN4 tetramer. d, Quantitation of the number of photobleaching steps. e, Velocity histogram of the kin14-VIb GCN4 tetramer with mean of 336 ± 97 nm s−1 (mean ± s.d., n=267). f, 1 – cumulative frequency for run lengths of the GCN4 tetramer construct, which were fitted to an exponential yielding a fit parameter of λ = 1.27±0.03 μm (error was determined from goodness of fit parameters; R2 = 0.995, n=267 particles).