Analysis and visualization of intermolecular interactions

Intermolecular interactions were detected using the PISA website tool³⁹ and visualized in UCSF Chimera. Hydrophobic interactions in the main figures were visualized as follows: For the first interactor, side chains of interfacing residues were shown in atom representation. For the second interactor, the interfacing residues were shown as surface and colored according to hydrophobicity in UCSF Chimera by the ‘Render by Attribute-Kd hydrophobicity’ function. To visualize the hydrophobic cores stabilizing the helical bundles of the GRIP domain core fold and the GRIP1-GRIP2 domain interface in Supplementary Fig. ³, the Spc α-helices were shown in ribbon representation and amino acid side chains were shown only for the residues contributing to the interaction. Electrostatic interactions were visualized as follows: The interfacing residues for both interactors were shown as surface and colored according to electrostatic properties in UCSF Chimera by the ‘Coulombic surface coloring’ function.