ATP-Dependent Transport of Phosphatidylserine Analogues in Human Erythrocytes
| Autor: | Smriti, David L. Daleke, Edward C. Nemergut |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Erythrocytes
ATPase Echinocyte Phospholipid Phosphatidylserines Biochemistry Substrate Specificity chemistry.chemical_compound Adenosine Triphosphate Humans Vanadate Enzyme Inhibitors Phospholipid Transfer Proteins Phospholipids Phosphatidylethanolamine biology Biological Transport Phosphatidylserine Flippase Membrane chemistry Ethylmaleimide biology.protein lipids (amino acids peptides and proteins) Vanadates |
| Zdroj: | Biochemistry. 46:2249-2259 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi061333x |
| Popis: | The plasma membrane of most cells contains a number of lipid transporters that catalyze the ATP-dependent movement of phospholipids across the membrane and assist in the maintenance of lipid asymmetry. The most well-characterized of these transporters is the erythrocyte aminophospholipid flippase, which selectively transports phosphatidylserine (PS) from the outer to the inner monolayer. Previous work has demonstrated that PS and to a lesser extent phosphatidylethanolamine (PE) are substrates for the flippase and that other phospholipids move across the membrane only by passive flip-flop. The present study re-evaluates these results. The incorporation and transbilayer movement of a number of short-chain (dilauroyl) phospholipid analogues in human erythrocytes was measured by observing lipid-induced changes in cell morphology, and the effect of an ATPase inhibitor (vanadate) and a sulfyhdryl reagent (N-ethylmaleimide) was determined. Incubation of cells with these lipids causes the rapid formation of echinocytes, because of the accumulation of the lipid in the outer monolayer. While dilauroylphosphatidylcholine-treated cells retained this shape, cells treated with sn-1,2-DLP-l-S, sn-1,2-DLP-d-S, or N-methyl-DLPS rapidly changed morphology to stomatocytes, which is consistent with the transport and accumulation of the lipid in the inner monolayer. A similar, although slower, stomatocytic shape change was induced by sn-2,3-DLP-l-S. Other lipids that were tested (dilauroylphosphatidylhydroxypropionate, dilauroylphosphatidylhomoserine, DLPS-methyl ester, or sn-2,3-DLP-d-S) reverted to discocytes only. In all cases, pretreatment with vanadate or N-ethylmaleimide inhibited the conversion of echinocytes to discocytes or stomatocytes. This is the first report of a protein- and energy-dependent pathway for the inwardly directed transbilayer movement of lipids other than PS and PE in the erythrocyte membrane and suggests that the flippase has broader specificity for substrates or that other lipid transporters are present. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|