Fig. 2.

HSP proteins spastin, atlastin 1, and REEP1 interact within the tubular ER membrane to coordinate ER shaping and MT dynamics (modified from Park et al. [7]). The three proteins (M1 spastin, atlastin 1, and REEP1) form protein complexes within the tubular ER, interacting with each other through hydrophobic hairpin domains in each of these proteins. The enlarge image shows the membrane topology of spastin, atlastin 1, and REEP1. The M1 isoform of the spastin ATPase binds to microtubules through its MIT domain and MTB domain, and is involved in microtubule severing, coupling changes in ER morphology with microtubule dynamics. Atlastin 1 interacts with spastin in their N-termini. REEP1 makes direct contact with the microtubular cytoskeleton through its C-terminal cytoplasmic domain.