title: Exposure of phosphatidylserine on the cell surface.
abstract: Phosphatidylserine (PtdSer) is a phospholipid that is abundant in eukaryotic plasma membranes. An ATP-dependent enzyme called flippase normally keeps PtdSer inside the cell, but PtdSer is exposed by the action of scramblase on the cell's surface in biological processes such as apoptosis and platelet activation. Once exposed to the cell surface, PtdSer acts as an 'eat me' signal on dead cells, and creates a scaffold for blood-clotting factors on activated platelets. The molecular identities of the flippase and scramblase that work at plasma membranes have long eluded researchers. Indeed, their identity as well as the mechanism of the PtdSer exposure to the cell surface has only recently been revealed. Here, we describe how PtdSer is exposed in apoptotic cells and in activated platelets, and discuss PtdSer exposure in other biological processes.
authors.affiliation: Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Nagata
authors.affiliation: Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Suzuki
authors.affiliation: Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Segawa
authors.affiliation: Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujii
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D010718:Phosphatidylserines / Q000378:metabolism*; D049294:Phospholipid Transfer Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D051017:Apoptosis Regulatory Proteins; D010718:Phosphatidylserines; D049294:Phospholipid Transfer Proteins; D020169:Caspases