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J Gen Physiol. 1973 October 1; 62(4): 375–391.
PMCID: PMC2226121

Destruction of Sodium Conductance Inactivation in Squid Axons Perfused with Pronase

Abstract

We have studied the effects of the proteolytic enzyme Pronase on the membrane currents of voltage-clamped squid axons. Internal perfusion of the axons with Pronase rather selectively destroys inactivation of the Na conductance (gNa). At the level of a single channel, Pronase probably acts in an all-or-none manner: each channel inactivates normally until its inactivation gate is destroyed, and then it no longer inactivates. Pronase reduces gNa, possibly by destroying some of the channels, but after removal of its inactivation gate a Na channel seems no longer vulnerable to Pronase. The turn-off kinetics and the voltage dependence of the Na channel activation gates are not affected by Pronase, and it is probable that the enzyme does not affect these gates in any way. Neither the K channels nor their activation gates are affected in a specific way by Pronase. Tetrodotoxin does not protect the inactivation gates from Pronase, nor does maintained inactivation of the Na channels during exposure to Pronase. Our results suggest that the inactivation gate is a readily accessible protein attached to the inner end of each Na channel. It is shown clearly that activation and inactivation of Na channels are separable processes, and that Na channels are distinct from K channels.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • ARMSTRONG CM, BINSTOCK L. ANOMALOUS RECTIFICATION IN THE SQUID GIANT AXON INJECTED WITH TETRAETHYLAMMONIUM CHLORIDE. J Gen Physiol. 1965 May;48:859–872. [PMC free article] [PubMed]
  • Bean RC, Shepherd WC, Chan H, Eichner J. Discrete conductance fluctuations in lipid bilayer protein membranes. J Gen Physiol. 1969 Jun;53(6):741–757. [PMC free article] [PubMed]
  • Bezanilla F, Armstrong CM. Negative conductance caused by entry of sodium and cesium ions into the potassium channels of squid axons. J Gen Physiol. 1972 Nov;60(5):588–608. [PMC free article] [PubMed]
  • Chandler WK, Meves H. Sodium and potassium currents in squid axons perfused with fluoride solutions. J Physiol. 1970 Dec;211(3):623–652. [PubMed]
  • COLE KS, MOORE JW. Ionic current measurements in the squid giant axon membrane. J Gen Physiol. 1960 Sep;44:123–167. [PMC free article] [PubMed]
  • Ehrenstein G, Lecar H, Nossal R. The nature of the negative resistance in bimolecular lipid membranes containing excitability-inducing material. J Gen Physiol. 1970 Jan;55(1):119–133. [PMC free article] [PubMed]
  • FRANKENHAEUSER B, HODGKIN AL. The action of calcium on the electrical properties of squid axons. J Physiol. 1957 Jul 11;137(2):218–244. [PubMed]
  • Hille B. Ionic channels in nerve membranes. Prog Biophys Mol Biol. 1970;21:1–32. [PubMed]
  • Hladky SB, Haydon DA. Discreteness of conductance change in bimolecular lipid membranes in the presence of certain antibiotics. Nature. 1970 Jan 31;225(5231):451–453. [PubMed]
  • HODGKIN AL, HUXLEY AF. A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol. 1952 Aug;117(4):500–544. [PubMed]
  • Krasne S, Eisenman G, Szabo G. Freezing and melting of lipid bilayers and the mode of action of nonactin, valinomycin, and gramicidin. Science. 1971 Oct 22;174(4007):412–415. [PubMed]
  • Mueller P, Rudin DO. Induced excitability in reconstituted cell membrane structure. J Theor Biol. 1963 May;4(3):268–280. [PubMed]
  • MULLINS LJ. An analysis of conductance changes in squid axon. J Gen Physiol. 1959 May 20;42(5):1013–1035. [PMC free article] [PubMed]
  • Mullins LJ. A single channel or a dual channel mechanism for nerve excitation. J Gen Physiol. 1968 Sep;52(3):550–556. [PMC free article] [PubMed]
  • Narahashi T, Anderson NC, Moore JW. Comparison of tetrodotoxin and procaine in internally perfused squid giant axons. J Gen Physiol. 1967 May;50(5):1413–1428. [PMC free article] [PubMed]
  • Narahashi T, Moore JW, Shapiro BI. Condylactis toxin: interaction with nerve membrane ionic conductances. Science. 1969 Feb 14;163(3868):680–681. [PubMed]
  • Narahashi T, Shapiro BI, Deguchi T, Scuka M, Wang CM. Effects of scorpion venom on squid axon membranes. Am J Physiol. 1972 Apr;222(4):850–857. [PubMed]
  • Rojas E, Armstrong C. Sodium conductance activation without inactivation in pronase-perfused axons. Nat New Biol. 1971 Feb 10;229(6):177–178. [PubMed]
  • Rojas E, Atwater I. Blocking of potassium currents by pronase in perfused giant axons. Nature. 1967 Aug 19;215(5103):850–852. [PubMed]
  • Shrager PG, Strickholm A, Macey RI. Chemical modification of crayfish axons by protein crosslinking aldehydes. J Cell Physiol. 1969 Aug;74(1):91–100. [PubMed]
  • TASAKI I, TAKENAKA T. EFFECTS OF VARIOUS POTASSIUM SALTS AND PROTEASES UPON EXCITABILITY OF INTRACELLULARLY PERFUSED SQUID GIANT AXONS. Proc Natl Acad Sci U S A. 1964 Sep;52:804–810. [PubMed]
  • TASAKII, WATANABE A, TAKENAKA T. Resting and action potential of intracellularly perfused squid giant axon. Proc Natl Acad Sci U S A. 1962 Jul 15;48:1177–1184. [PubMed]
  • Takenaka T, Yamagishi S. Morphology and electrophysiological properties of squid giant axons perfused intracellularly with protease solution. J Gen Physiol. 1969 Jan;53(1):81–96. [PMC free article] [PubMed]

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