Fig. 1.

PS transfer and PS/PI(4)P exchange activity of Osh6p and ORD8 measured with different PS subspecies. a Name and chemical structure of the different PS subspecies. b Description of FRET-based protocols to measure PS transfer from L_A to L_B liposomes using the NBD-C2_Lact sensor, and PI(4)P transfer along the opposite direction using NBD-PH_FAPP. c Initial transfer rates determined for each PS subspecies. Osh6p (200 nM) or ORD8 (240 nM) was added to L_A liposomes (200 μM total lipid), made of DOPC and containing a given PS species at 5%, mixed with L_B liposomes (200 μM) containing or not 5% 16:0/16:0-PI(4)P and 250 nM NBD-C2_Lact. Data are represented as mean ± s.e.m. (Osh6p, non-exchange condition, n = 3–16; Osh6p, exchange condition, n = 3–8; ORD8, non-exchange condition, n = 3–11; ORD8_, exchange condition, n = 3–7). Statistically significant differences between PS transfer rates measured under non-exchange and exchange conditions were determined using an unpaired Mann–Whitney U test; **** p < 0.0001, **p < 0.01, *p < 0.05, ns: not significant. d Initial PI(4)P transfer rate. L_B liposomes containing 5% 16:0/16:0-PI(4)P were mixed with L_A liposomes, containing or not a given PS species (at 5%), and with Osh6p (200 nM) or ORD8 (240 nM) in the presence of 250 nM NBD-PH_FAPP. Data are represented as mean ± s.e.m. (Osh6p, non-exchange condition, n = 9; Osh6p, exchange condition, n = 3–9; ORD8, non-exchange condition, n = 9; ORD8_, exchange condition, n = 3–10). An unpaired Mann–Whitney U test was used to determine the statistically significant differences between the PI(4)P transfer rates measured in non-exchange and exchange conditions; ****p < 0.0001 , **p < 0.01, *p < 0.05, ns: not significant. e Acceleration of PS transfer as a function of the acceleration of PI(4)P transfer determined from rates measured in non-exchange and exchange conditions with all PS subspecies