Hok1 is required for EE motility. (A) Morphology of wild type and Δhok1 mutants. (B) EE distribution and motility in wild type, EMD5 mutants expressing hok1 (EMD5 + Hok1), and Δhok1 mutants (Δhok1). Deletion or mutation of hok1 abolishes motility and induces EE clusters (arrowheads; asterisk in kymograph). Contrast-inverted kymographs show GFP-Rab5a fluorescence (EEs). See also Video 1. (C) Domain organization of selected Hook proteins. For accession numbers, see Materials and methods. (D) Contrast-inverted kymographs showing bidirectional motility of mCherry-Rab5a–labeled EEs and Hok1-GFP. Hok1 locates on all moving organelles (yellow lines in merged image). See also Video 2. Images in A, B, and D were adjusted in brightness, contrast, and γ settings. Horizontal bars are in micrometers, and vertical bars are in seconds.