Calpain-calpastatin and fusion. Fusibility of erythrocytes is determined by a protease-protease inhibitor [calpain-calpastatin] balance.
Rat erythrocytes fuse when treated with the membrane mobility agent, 2-(2-methoxyethoxy)ethyl-cis-8-(2-octylcyclopropyl)octanoate (A2C) and Ca2+, whereas human cells do not. Membrane proteolysis promoted by calpain is required for rat cell fusion [(1986) Eur. J. Biochem., in press]. Human calpain induced a selective proteolysis in both the human and rat erythrocyte ghosts (mainly band 4.1 in the human, band 4.1 and band 3 in the rat cell) and rendered them fusible. Calpastatin (calpain inhibitor) prevented A2C-induced fusion in both ghosts, via inhibition of proteolysis. The human erythrocyte has excess calpastatin and resists A2C-promoted fusion. A regulatory role of calpastatin in membrane fusion is thus indicated.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D002154:Calpain / Q000494:pharmacology*; D002459:Cell Fusion / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000502:physiology*; D006801:Humans; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D013045:Species Specificity; D013228:Stearates / Q000494:pharmacology
D002135:Calcium-Binding Proteins; D011480:Protease Inhibitors; D013228:Stearates; C023714:A(2)C; C033668:calpastatin; D002154:Calpain; D002118:Calcium