Supplementary Figure 4: ORP1L mediates ER contact sites through its FFAT motif.

a) Schematic representation of the gibberellin-induced dimerization system. ORP1L variants (WT and FFAT*) lacking ankyrin repeats were rendered soluble (ORP1L₇₄₇). These variants were linked to the smallest recruitable fragment of the gibberellin-insensitive protein GAI (GAI₉₂)⁴⁶ and tagged with mTurquoise2. A second construct consists of YFP-tagged gibberellin-insensitive dwarf1 (GID1) linked to the 11 amino acid tail of Lyn kinase that localizes to the plasma membrane. The plant hormone gibberellin binds GID1 causing a conformational change. The alternative GID1 conformation recruits the gibberellin-insensitive protein GAI. After addition of a cell permeant gibberellin analogue (GA₃-AM), the soluble mTq2-GAI₉₂-ORP1L₇₄₇ is recruited to the plasma membrane. b, c) Representative confocal micrographs of 3 independent experimental replicates showing HeLa cells expressing mCh-VAPB, YFP-GID1-Lyn11 and either mTq2-GAI₉₂-ORP1L₇₄₇ (b) or its FFAT* variant (c), after the addition of GA₃-AM.