1. Cytosolic coiled-coil proteins with conserved N-terminal domains, which attach to microtubules, and more divergent C-terminal domains, which mediate binding to organelles. Human hook1 (HK1; 719 aa) has 33% homology with the Drosophila protein, hook2 binds to different organelles, and hook3 is enriched in the cis-Golgi. Hook proteins are a subset of a larger family, hook-related proteins (HkRP) which all have the conserved domains found in hook proteins.
2. See AT hook.