If phosphatidylserine is the death knell, a new phosphatidylserine-specific receptor is the bellringer

Recognition of phosphatidylserine (PtdSer) is essential for engulfment of a poptotic cells by mammalian phagocytes. Engagement of a new phosphatidylser ine-specific receptor (PtdSerR) appears to be necessary for uptake of apopt otic cells. Many other mammalian receptors have been described to function in the clearance of apoptotic cells. The emerging picture is that many of t hese receptors may provide the strong adhesion needed to increase the likel ihood of contact between the PtdSerR and its phospholipid ligand, which is required for uptake. Furthermore, stimulation of this receptor on different types of phagocytes by apoptotic cells, PtdSer-containing liposomes or an IgM monoclonal anti-PtdSer antibody initiates release of TGF beta, known to be involved in the anti-inflammatory effects of apoptotic cells. Although highly homologous genes exist in C. elegans and Drosophila melanogaster, th eir role in engulfment of apoptotic cells remains to be determined.