Functional Ca²⁺ Channel Produced by Purified Platelet Membrane Glycoprotein IIb-IIIa Complex Incorporated into Planar Phospholipid Bilayer

Summary

The ability of the platelet membrane glycoprotein (GP) IIb-IIIa complex to function as a Ca²⁺ channel was investigated by electrophysiological methods. The GPIIb-IIIa complex was purified with an electrically silent detergent, CHAPS, and reconstituted into liposomes. After incorporation of these liposomes to a planar phospholipid bilayer, Ba²⁺-permeable channel currents were detected. Since neither residual detergent nor dissociated GPIIb and IIIa produced any currents, the observed channel currents were attributed to the GPIIb-IIIa complex. These channel currents showed similar electrical properties with the Ca²⁺ channel previously described in platelet plasma membrane; a single channel conductance of approximately 10 pS in 53 mM Ba²⁺ solution and voltage-independency. It was concluded that the purified GPIIb-IIIa complex can act as a divalent cation-permeable channel in the artificial phospholipid bilayer.

• References

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