OUT-TO-IN TRANSLOCATION OF BUTANETRIOL-CONTAINING PHOSPHOLIPID ANALOGS IN HUMAN ERYTHROCYTE-MEMBRANE

Fluorescent butanetriol-containing phospholipid analogs were synthesiz ed by replacing the glycerol moiety in ecanoyl-2-[6-N-(7-nitrobenz-2-o xa-1,3-diazol-4-yl) aminohexanoyl]-sn-glycero-3-phosphocholine, -phosp hoethanolamine, -phosphoserine and oxa-1,3-diazol-4-yl)aminododecanoyl ]-sn-glycero-3- phosphocholine, -phosphoethanolamine, -phosphoserine b y the 1,3,4-butanetriol residue, and their out-to-in translocation in the human erythrocyte membrane studied by 'back exchanging' the outer surface-incorporated phospholipids using bovine serum albumin. The res ults of these studies indicate that the replacement of the glycerol mo iety by the 1,3,4-butanetriol residue in aminophospholipids does not e ffect their out-to-in translocation in the human erythrocyte membrane. Furthermore, since earlier study by Arora and Gupta (Biochim. Biophys . Acta 1324 (1997) 47-60) has shown that the conformation of the 1,3,4 -butanetriol phospholipids possess the backbone conformation similar t o that of glycerophospholipids, it is suggested that besides the norma l phospholipid polar head-group, a normal phospholipid interface confo rmation may also be required for the aminophospholipid-translocase int eractions. (C) 1998 Elsevier Science B.V. All rights reserved.