Identification and purification of aminophospholipid flippases.
Transbilayer phospholipid asymmetry is a common structural feature of most biological membranes. This organization of lipids is generated and maintained by a number of phospholipid transporters that vary in lipid specificity, energy requirements and direction of transport. These transporters can be divided into three classes: (1) bidirectional, non-energy dependent 'scramblases', and energy-dependent transporters that move lipids (2) toward ('flippases') or (3) away from ('floppases') the cytofacial surface of the membrane. One of the more elusive members of this family is the plasma membrane aminophospholipid flippase, which selectively transports phosphatidylserine from the external to the cytofacial monolayer of the plasma membrane. This review summarizes the characteristics of aminophospholipid flippase activity in intact cells and describes current strategies to identify and isolate this protein. The biochemical characteristics of candidate flippases are critically compared and their potential role in flippase activity is evaluated.
Daleke
D L
DL
Department of Biochemistry and Molecular Biology and Medical Sciences Program, Indiana University, Bloomington 47405, USA. daleked@indiana.edu
Lyles
J V
JV
D000818:Animals; D001692:Biological Transport; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism*; D002837:Chromaffin Granules / Q000201:enzymology; D004910:Erythrocyte Membrane / Q000201:enzymology; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D009708:Nucleotidases / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D049294:Phospholipid Transfer Proteins; D013379:Substrate Specificity
D002352:Carrier Proteins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D010718:Phosphatidylserines; D049294:Phospholipid Transfer Proteins; D009708:Nucleotidases; D017301:Ca(2+) Mg(2+)-ATPase