Effects of proteolytic enzymes on ionic conductances of squid axon membranes

The Journal of Membrane Biology
C Sevcik, T Narahashi

Abstract

The effects of proteolytic enzymes on ionic conductances of squid axon membranes have been studied by means of the voltage clamp technique. When perfused internally alpha-chymotrypsin (1 mg/ml) increased and prolonged the depolarizing after-potential. Sodium inactivation was partially inhibited causing a prolonged sodium current, and peak sodium and steady-state potassium currents were suppressed. The time for sodium current to reach its peak was not affected. Leakage conductance increased later. On the other hand, carboxypeptidases A and B, both at 1mg/ml, suppressed the sodium and potassium conductance increases with little or no change in sodium inactivation. The mechanism that controls sodium inactivation appears to be associated with the structure of membrane proteins which is modified by alpha-chymotrypsin but not by carboxypeptidases and is located in a position accessible to alpha-chymotrypsin only from inside the membrane.

References

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May 1, 1967·Proceedings of the National Academy of Sciences of the United States of America·E Rojas, I Atwater
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Citations

Jun 1, 1993·Pflügers Archiv : European journal of physiology·P Proks, F M Ashcroft
Jan 1, 1979·Neuroscience·B I Khodorov
Mar 23, 2004·Toxicon : Official Journal of the International Society on Toxinology·G D'SuzeL D Possani
Mar 1, 1978·The Journal of General Physiology·G S OxfordT Narahashi
Feb 1, 1987·The Journal of General Physiology·T Gonoi, B Hille
Dec 8, 1982·Biochimica Et Biophysica Acta·E Carbone
Dec 29, 1977·Molecular and Cellular Biochemistry·F Hucho, W Schiebler
Feb 24, 1977·Nature·K S LeeA M Brown
Aug 11, 1975·The Journal of Membrane Biology·Y SoedaT Narahashi
Apr 21, 1984·Journal of Theoretical Biology·G Matsumoto

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