Enables phospholipid scramblase activity. Involved in engulfment of apoptotic cell; neutrophil clearance; and phosphatidylserine exposure on apoptotic cell surface. Acts upstream of or within establishment of localization in cell; positive regulation of myoblast differentiation; and tolerance induction to self antigen. Is active in plasma membrane. Orthologous to human XKR8 (XK related 8). [provided by Alliance of Genome Resources, Apr 2022]