Fusion of rat erythrocytes by membrane‐mobility agent A2C depends on membrane proteolysis by a cytoplasmic calpain

Tova GLASER, Nechama S. KOSOWER*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The membrane‐mobility agent 2‐(2‐methoxyethoxy)ethyl‐cis‐8‐(2‐octylcyclopropyl)octanoate (A2C) promotes fusion of rat, but not of human, erythrocytes. The difference in fusibility was shown to be correlated with membrane proteolysis, a process induced by Ca2+ in the rat erythrocytes or hemolysate‐loaded ghosts, but not in the human cell. Membrane proteolysis is necessary but not sufficient for fusion. Fusion requires both Ca2+ and A2C [Kosower, N. S., Glaser, T. and Kosower, E. M. (1983) Proc. Natl Acad. Sci USA 80, 7542–7546]. Membrane proteolysis (Ca2+‐dependent) and fusion (Ca2+ and A2C‐dependent) requires a Ca2+‐activated cytoplasmic thiol protease, as shown by the following observations. (a) In intact rat erythrocytes, proteolysis and fusion are prevented by thiol alkylation and by inhibitors of Ca2+‐dependent thiol proteases. Inhibitors to other proteases have no effect. (b) Erythrocyte ghosts undergo proteolysis and fusion only when loaded with non‐inhibited hemolysate, irrespective of membrane status (native or alkylated membrane). (c) A partially purified cytosolic enzyme, identified as calpain I, promotes proteolysis in rat erythrocyte ghosts. A2C induces fusion only in such calpain‐treated ghosts.

Original languageEnglish
Pages (from-to)387-392
Number of pages6
JournalEuropean Journal of Biochemistry
Volume159
Issue number2
DOIs
StatePublished - Sep 1986

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