The erythrocyte receptor for the channel-forming toxin aerolysin is a novel glycosylphosphatidylinositol-anchored protein.
The plasma membrane of rat erythrocytes contains a 47-kDa glycoprotein that binds the channel-forming toxin aerolysin with high affinity and accounts for the sensitivity of these cells to the toxin. The receptor was purified so that its N-terminal sequence could be determined after Western blotting. The sequence did not match any sequences in the databases, indicating that the receptor is a novel erythrocyte surface protein. However, it exhibited considerable homology to the N-termini of a group of membrane proteins that are thought to be involved in ADP-ribosyl transfer reactions. A common property of these proteins is that they are attached to plasma membranes by C-terminal glycosylphosphatidylinositol (GPI) anchors. The aerolysin receptor was shown to be anchored in the same way by treating rat erythrocytes with phosphatidylinositol-specific phospholipase C. This caused the selective release of the receptor and a reduction in the rodent cells' sensitivity to aerolysin. Human and bovine erythrocytes were shown to contain an aerolysin-binding protein with similar properties to the rat erythrocyte receptor. Proteins with GPI anchors are thought to have unusually high lateral mobility, and this may be an advantage for a toxin, such as aerolysin, which must oligomerize after binding to become insertion competent.
Cowell
S
S
Department of Biochemistry and Microbiology, University of Victoria, BC, Canada.
Aschauer
W
W
Gruber
H J
HJ
Nelson
K L
KL
Buckley
J T
JT
D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D002417:Cattle; D004912:Erythrocytes / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000302:isolation & purification / Q000378:metabolism*; D008051:Lipid Bilayers; D052899:Pore Forming Cytotoxic Proteins; D051381:Rats; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*
D001427:Bacterial Toxins; D017261:Glycosylphosphatidylinositols; D007473:Ion Channels; D008051:Lipid Bilayers; D052899:Pore Forming Cytotoxic Proteins; D011956:Receptors, Cell Surface; C032676:aerolysin