Erythrocyte Ca²⁺-dependent phospholipid scramblase 1, PLSCR1, of 318 aas and 1 or 2 C-terminal TMSs.  The C-terminal helix (CTH) inserts into the membrane via charge interactions but does not oligomerize in the membrane. The CTH is thus required for membrane insertion, Ca²⁺ coordination and the functional conformational changes that result in lipid scrambling (Francis et al. 2013).  The C-terminal region binds cholesterol (Posada et al. 2014). The role of this protein in phospholipid scrambling has been questioned (Sahu et al. 2007; Sivagnanam et al. 2017).