Proteolytic Activation of a Hyperpolarization- and Calcium-dependent Potassium Channel in Paramecium

Overview

Journal J Membr Biol

Date 1989 Nov 1

PMID 2687473

Citations 5

Authors

A Kubalski

B Martinac

Y Saimi

Affiliations

Soon will be listed here.

Abstract

The effects of proteolysis on a hyperpolarization- and Ca2+-dependent K channel from the surface membrane of Paramecium tetraurelia were examined in the inside-out excised patch mode. Treatment with trypsin, pronase or thermolysin removed the Ca2+-dependence of the channel activation, yielding an increase in channel activity greater than 2.5-fold at all Ca2+ concentrations between 10(-4) and 10(-8) M. Thermolysin additionally removed the voltage dependence of channel opening and gave the most activation among the three proteases tested. Proteolysis did not affect the single-channel conductance. In an analogy to the mechanism of activation of many Ca2+-dependent enzymes it is suggested that this Paramecium channel has a cytoplasmic inhibitory domain which can be removed by proteolysis, and that the physiological activation by Ca2+ is due to a temporary removal of this inhibition. Moreover, these findings indicate structural differences between depolarization-, Ca2+-dependent K channels (BK channels) and the hyperpolarization-, Ca2+-dependent K channels in Paramecium.

Citing Articles

Insights into potassium channel family and their biological functions.

Paul A, Chumbale S, Lakra A, Kumar V, Alhat D, Singh S 3 Biotech. 2023; 13(8):266.

PMID: 37425093 PMC: 10326225. DOI: 10.1007/s13205-023-03692-y.

Ion channels in microbes.

Martinac B, Saimi Y, Kung C Physiol Rev. 2008; 88(4):1449-90.

PMID: 18923187 PMC: 2579964. DOI: 10.1152/physrev.00005.2008.

Electrical responses of the marine ciliate Euplotes vannus (hypotrichia) to mechanical stimulation at the posterior cell end.

Kruppel T, Furchbrich V, Leuken W J Membr Biol. 1993; 135(3):253-60.

PMID: 8271265 DOI: 10.1007/BF00211097.

Calcium-dependent potassium channel in Paramecium studied under patch clamp.

Saimi Y, Martinac B J Membr Biol. 1989; 112(1):79-89.

PMID: 2593141 DOI: 10.1007/BF01871166.

A mechanosensitive ion channel in Schizosaccharomyces pombe.

Zhou X, Kung C EMBO J. 1992; 11(8):2869-75.

PMID: 1379173 PMC: 556767. DOI: 10.1002/j.1460-2075.1992.tb05355.x.

References

Pallotta B . N-bromoacetamide removes a calcium-dependent component of channel opening from calcium-activated potassium channels in rat skeletal muscle. J Gen Physiol. 1985; 86(5):601-11. PMC: 2228816. DOI: 10.1085/jgp.86.5.601. View

Saimi Y, Martinac B . Calcium-dependent potassium channel in Paramecium studied under patch clamp. J Membr Biol. 1989; 112(1):79-89. DOI: 10.1007/BF01871166. View

Matteson D, Carmeliet P . Modification of K channel inactivation by papain and N-bromoacetamide. Biophys J. 1988; 53(4):641-5. PMC: 1330237. DOI: 10.1016/S0006-3495(88)83143-6. View

Cornejo M, Guggino S, Guggino W . Modification of Ca2+-activated K+ channels in cultured medullary thick ascending limb cells by N-bromoacetamide. J Membr Biol. 1987; 99(2):147-55. DOI: 10.1007/BF01871234. View

Blatz A, Magleby K . Single apamin-blocked Ca-activated K+ channels of small conductance in cultured rat skeletal muscle. Nature. 1986; 323(6090):718-20. DOI: 10.1038/323718a0. View

Moczydlowski E, Latorre R . Gating kinetics of Ca2+-activated K+ channels from rat muscle incorporated into planar lipid bilayers. Evidence for two voltage-dependent Ca2+ binding reactions. J Gen Physiol. 1983; 82(4):511-42. PMC: 2228654. DOI: 10.1085/jgp.82.4.511. View

Rojas E, Rudy B . Destruction of the sodium conductance inactivation by a specific protease in perfused nerve fibres from Loligo. J Physiol. 1976; 262(2):501-31. PMC: 1307656. DOI: 10.1113/jphysiol.1976.sp011608. View

Noda M, Ikeda T, Kayano T, Suzuki H, Takeshima H, Kurasaki M . Existence of distinct sodium channel messenger RNAs in rat brain. Nature. 1986; 320(6058):188-92. DOI: 10.1038/320188a0. View

Walsh M, Dabrowska R, Hinkins S, Hartshorne D . Calcium-independent myosin light chain kinase of smooth muscle. Preparation by limited chymotryptic digestion of the calcium ion dependent enzyme, purification, and characterization. Biochemistry. 1982; 21(8):1919-25. DOI: 10.1021/bi00537a034. View

10.

ARMSTRONG C, Bezanilla F, Rojas E . Destruction of sodium conductance inactivation in squid axons perfused with pronase. J Gen Physiol. 1973; 62(4):375-91. PMC: 2226121. DOI: 10.1085/jgp.62.4.375. View

11.

Tempel B, Papazian D, Schwarz T, Jan Y, Jan L . Sequence of a probable potassium channel component encoded at Shaker locus of Drosophila. Science. 1987; 237(4816):770-5. DOI: 10.1126/science.2441471. View

12.

Sevcik C, Narahashi T . Effects of proteolytic enzymes on ionic conductances of squid axon membranes. J Membr Biol. 1975; 24(3-4):329-39. DOI: 10.1007/BF01868630. View

13.

Methfessel C, Boheim G . The gating of single calcium-dependent potassium channels is described by an activation/blockade mechanism. Biophys Struct Mech. 1982; 9(1):35-60. DOI: 10.1007/BF00536014. View

14.

Miller C, Rosenberg R . Modification of a voltage-gated K+ channel from sarcoplasmic reticulum by a pronase-derived specific endopeptidase. J Gen Physiol. 1979; 74(4):457-78. PMC: 2228560. DOI: 10.1085/jgp.74.4.457. View

15.

TUCKER M, Robinson Jr J, Stellwagen E . The effect of proteolysis on the calmodulin activation of cyclic nucleotide phosphodiesterase. J Biol Chem. 1981; 256(17):9051-8. View

16.

Niggli V, Adunyah E, Carafoli E . Acidic phospholipids, unsaturated fatty acids, and limited proteolysis mimic the effect of calmodulin on the purified erythrocyte Ca2+ - ATPase. J Biol Chem. 1981; 256(16):8588-92. View

17.

Rojas E, Armstrong C . Sodium conductance activation without inactivation in pronase-perfused axons. Nat New Biol. 1971; 229(6):177-8. DOI: 10.1038/newbio229177a0. View