Figure 1.

Phosphatidylserine (PS) is a central player in the recognition and engulfment of apoptotic cells. PS may be recognized by a variety of tethering receptors (shown as a single entity in green) and bridging molecules (shown as a single entity in pink) that help tether the apoptotic target to the phagocyte. The PS receptor signals to a pathway that leads to engulfment, for example by rearranging elements of the cytoskeleton (shown as cross-hatching). The proteins that correspond to the PS receptor, the aminophospholipid translocase (APLT), and the scramblase are unknown, as are the functions of ABCA1 and the PS exposed on the surface of the phagocyte. PSRp denotes the protein encoded by the psr gene, which is found within the nucleus.