cofactor:Calcium.,function:May mediate accelerated ATP-independent bidirectional transbilayer migration of phospholipids upon binding calcium ions that results in a loss of phospholipid asymmetry in the plasma membrane. May play a central role in the initiation of fibrin clot formation, in the activation of mast cells and in the recognition of apoptotic and injured cells by the reticuloendothelial system.,similarity:Belongs to the phospholipid scramblase family.,tissue specificity:Expressed in heart, placenta, lung, liver, skeletal muscle, kidney, pancreas, spleen, thymus, prostate, uterus, small intestine and peripheral blood lymphocytes. Not detected in testis, brain and liver.,