Cytoskeleton-associated protein 4, CKAP4, of 602 aas and one or two adjacent TMSs near the N-terminus. It mediates the anchoring of the endoplasmic reticulum to microtubules (Vedrenne et al. 2005). Palmitoylated CKAP4 regulates mitochondrial functions through an interaction with VDAC2 at ER-mitochondrion contact sites (Harada et al. 2020).