Affordable Access

Publisher Website

Fast translocation of phosphatidylcholine to the outer membrane leaflet after its synthesis at the inner membrane surface in human erythrocytes

Authors
Journal
Biochimica et Biophysica Acta (BBA) - Biomembranes
0005-2736
Publisher
Elsevier
Publication Date
Volume
1064
Issue
2
Identifiers
DOI: 10.1016/0005-2736(91)90307-t
Keywords
  • Phosphatidylcholine
  • Flip-Flop
  • Acyl-Coa
  • Arginine
  • Temperature Dependence
  • (Human Erythrocyte)
Disciplines
  • Biology

Abstract

Abstract The translocation rate of [ 14C]phosphatidylcholine to the outer membrane leaflet of human erythrocytes after its primary synthesis from lysophosphatidylcholine by acylation with 14C-labeled oleic or palmitic acid in the inner leaflet has been measured by following the time-dependent increase of cleavability of 14C-labeled phospholipids by external phospholipase A 2 (5 min, 37°C). Immediately after a short acylation time period of 10 min about 20% of the newly synthesized [ 14C]phosphatidylcholine are already detectable in the outer leaflet. After an incubation of 1 h at 37°C following 10 min of acylation the fractions of labeled and native phosphatidylcholine accessible to the lipase are identical, which demonstrates that [ 14C]phosphatidylcholine has attained the same asymmetric distribution as its endogenous analogue. The calculated halftime of the outward translocation is about 20 min and its activation energy is low, 30 kJ/mol. Translocation is inhibited by a 5 min treatment with phenylglyoxal following acylation. A fast translocation is not observed for newly synthesized phosphatidylethanolamine. Results suggest a selective, protein-mediated outward translocation of newly synthesized phosphatidylcholine.

There are no comments yet on this publication. Be the first to share your thoughts.