Both FAM102A and FAM102B interact with BLTP2. (A) Sequence alignment of human FAM102A and FAM102B, where their N-terminal C2 domains (purple dashed box) and their C-terminal predicted BLTP2-interacting regions (red dashed box) are highlighted. (B) Co-localization of FAM102A-GFP (top) and FAM102B-GFP (bottom) with BLTP2^Halo at ER-PM contact sites in MDA-MB-231 cells. (C) AlphaFold3 predicted interaction between FAM102B and BLTP2. (D) COS-7 cell co-expressing BLTP2^EGFP and BLTP2^Halo-△FBM with FAM102B-iRFP showing that BLTP2^Halo-△FBM is not co-enriched with WT BLTP2^EGFP at ER-PM contact sites but remains diffuse throughout the ER. (E) FAM102A-GFP recruits BLTP2^Halo to ER-PM contact sites in HeLaM cells. (F) Domain cartoon of the FAM102A-B chimeras. “+” indicates positive localization on tubular structures, and “−” indicates negative localization on tubular structures. (G) The FAM102A-B Chimera-EGFP is enriched at BLTP2-positive tubular structures in HeLaM cells.