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[Preprint]. 2024 Jul 11:2024.07.11.603126. [Version 1] doi: 10.1101/2024.07.11.603126

Figure 7. Morphologies of membrane tubules generated by endosomal coat complexes across different lipid and cargo compositions in vitro.

Figure 7.

Schematic comparison of endosomal coat complex combinations that generate tubules in the presence of physiological lipid and cargo compositions in vitro. Different endosomal coat proteins, either alone or as a complex, produce membrane tubules having different physical diameters as observed in negative stain EM (Table 3). SNX27 alone (A) or SNX27/Retromer (B) are shown here to generate tubules in the presence of PDZbm cargo and PI(3)P. (C) ESCPE-1 binds membrane containing Folch and CI-MPR cargo motifs, but does not interact with Retromer under these conditions. (D) The assembly of all individual coat components (SNX27, Retromer, and ESCPE-1) into the proposed endosomal ‘supercomplex’ occurs on membranes with PI(3)P and PDZbm cargo motifs only in the presence of VARP. The stoichiometry quantified using BLI (Figure 1) suggests one VARP may bind one SNX27 and two Retromer copies in an arch and promote a conformation allowing the SNX27 FERM domain to bind the flexible SNX2 N-terminus. (Figure created using BioRender.)