Rocha-Roa, C.; Sidhu, G.; Blair, P. C.; Alvarez, D.; Davey, M.; Conibear, E.; Vanni, S.

Bulk lipid transport between organelles has been proposed to involve the partnership between bridge lipid transport proteins and membrane-embedded lipid scramblases. However, for almost all BLTPs, such physical association has not been fully described, and, in most cases, the identity of the scramblases is unknown. Here, we identify TMEM170 family proteins as endoplasmic reticulum lipid scramblases that physically interact with BLTP1/Csf1 proteins. This finding opens new avenues to understand the complex mechanism involved in lipid transport at membrane contact sites.