Kalicludines and Kaliseptine

New peptides have been isolated from the sea anemone Anemonia sulcata which inhibit competitively the binding of 125I-dendrotoxin I (a classical ligand for K+ channel) to rat brain membranes and behave as blockers of voltage-sensitive K+ channels. Sea anemone kalicludines are 58-59-amino acid peptides cross-linked with three disulfide bridges. They are structurally homologous both to dendrotoxins which are snake venom toxins and to the basic pancreatic trypsin inhibitor (Kunitz inhibitor) and have the unique property of expressing both the function of dendrotoxins in blocking voltage-sensitive K+ channels and the function of the Kunitz inhibitor in inhibiting trypsin. Kaliseptine is another structural class of peptide comprising 36 amino acids with no sequence homology with kalicludines or with dendrotoxins. In spite of this structural difference, it binds to the same receptor site as dendrotoxin and kalicludines and is as efficient as a K+ channel inhibitor as the most potent kalicludine. New peptides have been isolated from the sea anemone Anemonia sulcata which inhibit competitively the binding of 125I-dendrotoxin I (a classical ligand for K+ channel) to rat brain membranes and behave as blockers of voltage-sensitive K+ channels. Sea anemone kalicludines are 58-59-amino acid peptides cross-linked with three disulfide bridges. They are structurally homologous both to dendrotoxins which are snake venom toxins and to the basic pancreatic trypsin inhibitor (Kunitz inhibitor) and have the unique property of expressing both the function of dendrotoxins in blocking voltage-sensitive K+ channels and the function of the Kunitz inhibitor in inhibiting trypsin. Kaliseptine is another structural class of peptide comprising 36 amino acids with no sequence homology with kalicludines or with dendrotoxins. In spite of this structural difference, it binds to the same receptor site as dendrotoxin and kalicludines and is as efficient as a K+ channel inhibitor as the most potent kalicludine. INTRODUCTIONPotassium channels have an essential role in repolarization phases of action potentials and in the fine regulation of the resting potential. Molecular cloning has recently led to the identification of a large number (over 15) of genes for voltage-sensitive, non inward-rectifier, K+ (Kv) channels (1Pongs O. Physiol. Rev. 1992; 72: S69-S88Crossref PubMed Google Scholar, 2Jan L.Y. Jan Y.N. Trends Neurosci. 1990; 13: 415-419Abstract Full Text PDF PubMed Scopus (158) Google Scholar) which, when expressed in Xenopus oocytes, generate a variety of K+ channel activities with different kinetics, voltage dependences, conductances, and regulation properties. Surprisingly, only a relatively small number of toxins active on these channels has yet been discovered(3Moczydlowski E. Lucchesi K. Ravidran A. J. Membr. Biol. 1988; 105: 95-111Crossref PubMed Scopus (184) Google Scholar, 4Meves H. Herken H. Hucho F. Handbook of Experimental Pharmacology. 102. Springer Verlag, Berlin1992: 739-774Google Scholar). They are MCD peptide from bee venom(5Bidard J.-N. Mourre C. Lazdunski M. Biochem. Biophys. Res. Commun. 1987; 143: 383-389Crossref PubMed Scopus (58) Google Scholar, 6Rehm H. Bidard J.-N. Schweitz H. Lazdunski M. Biochemistry. 1988; 27: 1827-1832Crossref PubMed Scopus (55) Google Scholar), charybdotoxin and analogs from different scorpion species (7Schweitz H. Stansfeld C.E. Bidard J.-N. Fagni L. Maes P. Lazdunski M. FEBS Lett. 1989; 250: 519-522Crossref PubMed Scopus (48) Google Scholar, 8Schweitz H. Bidard J.-N. Maes P. Lazdunski M. Biochemistry. 1989; 28: 9708-9714Crossref PubMed Scopus (39) Google Scholar, 9MacKinnon R Reinhart P.H. White M.M. Neuron. 1988; 1: 997-1001Abstract Full Text PDF PubMed Scopus (111) Google Scholar, 10Garcia M.L. Garcia-Calvo M. Hidalgo P. Lee A. MacKinnon R. Biochemistry. 1994; 33: 6834-6839Crossref PubMed Scopus (244) Google Scholar, 11Garcia-Calvo M. Leonard R.J. Novick J. Stevens S.P. Schmalhofer W. Kaczorowski G.J. Garcia M.L. J. Biol. Chem. 1993; 268: 18866-18874Abstract Full Text PDF PubMed Google Scholar, 12Possani L.D. Martin B.M. Svendsen I.B. Carlsberg Res. Commun. 1982; 47: 285-289Crossref Scopus (150) Google Scholar, 13Rogawski R.S. Krueger B.K. Collins J.H. Blaustein M.P. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: 1475-1479Crossref PubMed Scopus (92) Google Scholar, 14Grissmer S. Nguyen A.N. Aiyar J. Hanson D.C. Mather R.J. Gutman G.A. Karmilowicz M.J. Auperin D.D. Chandy K.G. Mol. Pharmacol. 1994; 45 (1227-1134)PubMed Google Scholar), β-bungarotoxin(15Schmidt R.R. Betz H. Rehm H. Biochemistry. 1988; 27: 963-967Crossref PubMed Scopus (42) Google Scholar, 16Awan K.A. Dolly J.O. Neuroscience. 1991; 40: 29-39Crossref PubMed Scopus (53) Google Scholar), and dendrotoxins from mamba venoms (3Moczydlowski E. Lucchesi K. Ravidran A. J. Membr. Biol. 1988; 105: 95-111Crossref PubMed Scopus (184) Google Scholar, 5Bidard J.-N. Mourre C. Lazdunski M. Biochem. Biophys. Res. Commun. 1987; 143: 383-389Crossref PubMed Scopus (58) Google Scholar, 17Harvey A.L. Anderson A.J. Harvey A.L. Snake Toxins. Pergamon Press, Inc., New York1991: 131-164Google Scholar, 18Rehm H. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 4919-4923Crossref PubMed Scopus (170) Google Scholar, 19Benishin C.G. Sorensen R.G. Brown W.E. Krueger B.K. Blaustein M.P. Mol. Pharmacol. 1988; 34: 152-159PubMed Google Scholar, 20Halliwell J.V. Othman I.B. Pelchen-Matthews A. Dolly J.O. Proc. Natl. Acad. Sci. U. S. A. 1986; 83: 493-497Crossref PubMed Scopus (175) Google Scholar, 21Dreyer F. Rev. Physiol. Biochem. Pharmacol. 1990; 115: 93-136Crossref PubMed Google Scholar, 22Rehm H. Eur. J. Biochem. 1991; 202: 701-713Crossref PubMed Scopus (29) Google Scholar).These different toxins only block the expression of four of the cloned Kv channels (Kv1.1, Kv1.2, and Kv1.6 for MCD peptide and dendrotoxin, Kv1.1, Kv1.2, Kv1.3, and Kv1.6 for charybdotoxin) (reviewed in (23Pongs O. Trends Pharmacol. Sci. 1992; 13: 359-365Abstract Full Text PDF PubMed Scopus (73) Google Scholar)). Binding studies using radioiodinated derivatives of these toxins have been essential for the identification, purification, and determination of the subunit structure (6Rehm H. Bidard J.-N. Schweitz H. Lazdunski M. Biochemistry. 1988; 27: 1827-1832Crossref PubMed Scopus (55) Google Scholar, 24Rehm H. Lazdunski M. Biochem. Biophys. Res. Commun. 1988; 153: 231-240Crossref PubMed Scopus (34) Google Scholar, 25Betz H. Biochemistry. 1990; 29: 3591-3599Crossref PubMed Scopus (130) Google Scholar, 26Scott V.E.S. Rettig J. Parcej D.N. Keen J.N. Findlay J.B.C. Pongs O. Dolly J.O. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: 1637-1641Crossref PubMed Scopus (176) Google Scholar) of these Kv channels. These toxins have also been important for the first brain localizations of Kv channels (16Awan K.A. Dolly J.O. Neuroscience. 1991; 40: 29-39Crossref PubMed Scopus (53) Google Scholar, 27Bidard J.-N. Mourre C. Gandolfo G. Schweitz H. Widmann C. Gotessmann C. Lazdunski M. Brain Res. 1989; 495: 45-57Crossref PubMed Scopus (48) Google Scholar) and are particularly interesting inducers of long term potentiation(28Cherubini E. Ben Ari Y. Gho M. Bidard J.-N. Lazdunski M. Nature. 1987; 328: 70-73Crossref PubMed Scopus (85) Google Scholar).Sea anemones produce toxins with which they paralyze their prey. They are particularly important as sources of toxins active on voltage-dependent Na+ channel which have been essential tools for studying the structure, the mechanism, and the diversity of this channel type(29Fritz H. Brey B. Béress L. Hoppe-Seyler's Z. Physiol. Chem. 1972; 353: 19-30Crossref PubMed Scopus (68) Google Scholar, 30Béress L. Béress R. Wunderer G. FEBS Lett. 1975; 50: 311-314Crossref PubMed Google Scholar, 31Romey G. Abita J.-P. Schweitz H. Wunderer G. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1976; 73: 4055-4059Crossref PubMed Scopus (158) Google Scholar, 32Béress L. Kaul P.N. Sindermann C.J. Drugs and Food from the Sea, Myth or Reality? The University of Oklahoma Press, Norman, OK1978: 59-72Google Scholar, 33Vincent J.-P. Balerna M. Barhanin J. Fosset M. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1980; 77: 1646-1650Crossref PubMed Scopus (71) Google Scholar, 34Barhanin J. Hugues M. Schweitz H. Vincent J.-P. Lazdunski M. J. Biol. Chem. 1981; 256: 5764-5769Abstract Full Text PDF PubMed Google Scholar, 35Frelin C. Vigne P. Schweitz H. Lazdunski M. Mol. Pharmacol. 1984; 26: 70-74PubMed Google Scholar, 36Schweitz H. Bidard J.-N. Frelin C. Lazdunski M. F. A. Biochemistry. PubMed Scopus Google Scholar, M. Frelin C. Barhanin J. A. H. G. A. Schweitz H. Vigne P. Y. Acad. Sci. 1987; Scopus Google Scholar, R.S. 1991; 29: PubMed Scopus Google the structure, and of a of toxins from Anemonia sulcata which behave as blockers of Kv the Kunitz trypsin inhibitor pancreatic trypsin inhibitor also when from I from and from from and from from from from and from with a of Anemonia first of this with of a for the of Na+ channel toxins of A. E. G. A. Béress L. Hucho F. and Scholar). In this of the sea anemone E. G. A. Béress L. Hucho F. and in of and in on a in The of these in a for and on a with a and this sea anemone toxins on a as in which active on K+ channels and are These their to inhibit binding of the of dendrotoxin I of the most potent of Kv channels. The peptides as and They and on in acid and The for peptide as on of of sea anemone from A. sulcata as The with the and in this a as in the The with the and are of and as are of The peptide is the of in the same as in for a acid and in a of for the and different acid in and the same in for the three different the for their to inhibit binding to receptor in rat brain the peptides and on with of acid in and The peptides first in and with and of Anemonia Kaliseptine from in on a with as The in three the first on and of it in an and with a from to in in the first important and and on the same from to in the same of and 36 as in of Anemonia from on in with as in the The first on and the as for of the on the in the and and on the in the and this on a with a and in as in and of Anemonia from first on also the first of the three The as for with of the on the in the and and on the in the and 45 this on the the same as for the of as in and of Anemonia in this is the and most basic on with and a and in the of Na+ channel toxins from A. H. Vincent J.-P. Barhanin J. Frelin C. G. Hugues M. Lazdunski M. Biochemistry. 1981; PubMed Scopus (111) Google Scholar). of this on the in the and The in of and of on an a of with a from to in as in and as the The of is in of the and using an of to M.J. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). The sequence for and sequence determination of the peptides of of peptides in for with of The and in peptide a using an acid in with a of and the to with acid and using a of of the using a the for the to from the in and of with the sea anemone B. to of from a of and binding of to rat brain membranes as J.-N. Mourre C. Gandolfo G. Schweitz H. Widmann C. Gotessmann C. Lazdunski M. Brain Res. 1989; 495: 45-57Crossref PubMed Scopus (48) Google for Xenopus with the cloned and have been E. E. L. F. Schweitz H. B. Barhanin J. Lazdunski M. Biochemistry. 1992; PubMed Scopus Google Scholar). The and in of of trypsin and the inhibitor and A. sulcata peptides of trypsin the of for in in the of of the peptides in a of 45 the trypsin of of in of using the of from and M. M. Biol. 1994; 1: PubMed Scopus (55) Google Scholar) and A. J. R. J. Mol. Biol. 1987; PubMed Scopus Google Scholar) from the O. M. J. Mol. Biol. PubMed Scopus Google Scholar). The peptide sequence of to the of dendrotoxin in the and the have from the sea anemone A. sulcata four peptides for their to binding to in rat is a of K+ channels and these A. sulcata peptides only inhibit binding also inhibit K+ channel it has been to the of A. sulcata and kalicludines and and the of the four of have sequence with and the basic trypsin inhibitor (Kunitz which is a of A.L. Anderson A.J. Harvey A.L. Snake Toxins. Pergamon Press, Inc., New York1991: 131-164Google Scholar). These toxins A. sulcata kalicludines and they also have structural with another of the Kunitz inhibitor and of M. M. Biol. 1994; 1: PubMed Scopus (55) Google Scholar, H. C. P. G. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: PubMed Scopus Google Scholar) which is a of voltage-sensitive channels. The peptide is homologous to A. sulcata the of the of binding the different sea anemone of are for for for and for These of the for of binding which is in both and kalicludines inhibit binding in a of the the toxins the of which are for and for of the three kalicludines binding to in rat brain to the of they are also structurally homologous to this channel blocking H. C. P. G. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: PubMed Scopus Google the Kunitz trypsin and different peptides from A. sulcata of the binding to rat brain and the different peptides first different with the membranes and and membranes for are of binding and the Kunitz inhibitor of to rat brain membranes in the of different of and of for with for binding of binding in the are of is expressed as of of of of of A. sulcata peptides on the is the in the of in these peptides from A. sulcata which also inhibit the K+ channel expressed in Xenopus as The for of the from for to for to for to for these has an of which inhibit the with the are also which have the for the of the K+ in Xenopus expressing the channels. The with of In these the and The in and in the of peptide the three kalicludines have with which is a potent of trypsin it kalicludines also have an to inhibit trypsin. the of first for with different of the kalicludines to to the trypsin to from three kalicludines inhibit trypsin. of trypsin and are of trypsin of a of the The of with and a is when the for the is of the of trypsin in the J.-P. Lazdunski M. Biochemistry. 1972; PubMed Scopus Google Scholar), the of of these sea anemone peptides with trypsin has to also a large of another Kv channel of structure, is to inhibit trypsin. of trypsin also for from another dendrotoxin for K+ channels A.L. Anderson A.J. Harvey A.L. Snake Toxins. Pergamon Press, Inc., New York1991: 131-164Google Scholar) which is structurally to the Kunitz inhibitor it has a in to the essential the active site of the trypsin inhibitor J.-P. Schweitz H. Lazdunski M. Eur. J. Biochem. PubMed Scopus Google Scholar) is a in A. sulcata which has no structural homology with inhibit trypsin a of to of trypsin different of A. sulcata and dendrotoxins. from is the of the different peptides to trypsin in the first of peptides isolated in this has been A. sulcata They inhibit binding to Kv channel and block the channel expressed in the Xenopus Sea anemone kalicludines and are amino acid peptides homologous to of the Kunitz and to dendrotoxins They have from to with the Kunitz inhibitor and from to with These sequence led to their with of these is the most potent of the E. E. L. F. Schweitz H. B. Barhanin J. Lazdunski M. Biochemistry. 1992; PubMed Scopus Google Scholar). for receptor in rat brain is as also in the is the most potent inhibitor of trypsin with a of J.-P. Lazdunski M. Biochemistry. 1972; PubMed Scopus Google Scholar) is a of Kv and A. sulcata kalicludines are with of They have both the of and they binding to channel in a and they inhibit trypsin in a in of these trypsin is and as the class of sea anemone K+ channel which is structurally different from the inhibit trypsin. is the first both of a K+ channel and a potent of a have been in a of amino acids and structurally to inhibit and Harvey A.L. Biol. Chem. 1992; PubMed Scopus Google Scholar).Sea anemones and it as kalicludines are of a and has for to for trypsin or for of the voltage-sensitive K+ structure of dendrotoxins and is in to of and of The of the peptide sequence of in the of the structure of only a of and and and the only of the of the of and the the of both and are and the same These amino acids are and and of is and of the structure of dendrotoxin I using J. 1991; Google Scholar) and the of the M. M. Biol. 1994; 1: PubMed Scopus (55) Google Scholar, O. M. J. Mol. Biol. PubMed Scopus Google Scholar). are in a The trypsin binding site in is in the in dendrotoxin of to in dendrotoxin I and amino acids and are in amino acids and in and the in In the the are in the same as in In the the structure and are on the and The is a and the of the in a The is an the trypsin binding in dendrotoxins are to inhibit trypsin has J. Mol. Biol. 1992; PubMed Scopus Google Scholar). of both the of a and a amino acid in dendrotoxin and in produce a with the trypsin active the in of a in is an in has been as an for with of trypsin. these three for a of trypsin and are in which is the to in dendrotoxins is the has as it is a trypsin property with an which of has been recently M. M. Biol. 1994; 1: PubMed Scopus (55) Google Scholar) the most structural and dendrotoxins which the of in their to block K+ channels. The in the and in the and are to the peptide are in when and the and in is another of and in of in the are in to with a sequence of The on in I is in as as the on of in structure of is different from of is also a peptide 36 amino has no homology with of the Kunitz with a acid peptide isolated from another sea which is also a of the voltage-dependent K+ to it A. Harvey A.L. Anderson A.J. U. E. Biophys. 1993; PubMed Scopus Google Scholar). these have a in the of of their and in the is as for are to disulfide bridges. from a in the sequence of the B. and also have with a acid inhibitor from the of a sea A. Harvey A.L. Anderson A.J. U. E. Biophys. 1993; PubMed Scopus Google Scholar, Proc. Scholar) which has with with are to the sequence of the sea inhibitor and to the sequence which is homologous to of with a trypsin inhibitor they have been with a only channels also and Kv1.6 channels when they are expressed in Xenopus as as channels of different to these different of O. Physiol. Rev. 1992; 72: S69-S88Crossref PubMed Google Scholar, 2Jan L.Y. Jan Y.N. Trends Neurosci. 1990; 13: 415-419Abstract Full Text PDF PubMed Scopus (158) Google Scholar). the of sea anemone kalicludines and to inhibit binding to membranes is to their to inhibit expression of a class of K+ channel this binding a of of voltage-sensitive K+ S. Nguyen A.N. Aiyar J. Hanson D.C. Mather R.J. Gutman G.A. Karmilowicz M.J. Auperin D.D. Chandy K.G. Mol. Pharmacol. 1994; 45 (1227-1134)PubMed Google Scholar, O. Trends Pharmacol. Sci. 1992; 13: 359-365Abstract Full Text PDF PubMed Scopus (73) Google Scholar, 24Rehm H. Lazdunski M. Biochem. Biophys. Res. Commun. 1988; 153: 231-240Crossref PubMed Scopus (34) Google Scholar). these a of the different toxins in this have to on different of Kv as for O. Trends Pharmacol. Sci. 1992; 13: 359-365Abstract Full Text PDF PubMed Scopus (73) Google Scholar). of these peptides which are in relatively or in a it has been a particularly interesting property of sea anemone venom is it only toxins different of voltage-sensitive Na+ channels in different of a also Na+ channels in different C. Vigne P. Schweitz H. Lazdunski M. Mol. Pharmacol. 1984; 26: 70-74PubMed Google Scholar, M. Frelin C. Barhanin J. A. H. G. A. Schweitz H. Vigne P. Y. Acad. Sci. 1987; Scopus Google Scholar). number of the sea anemone toxins for Na+ channels have only a small a H. Vincent J.-P. Barhanin J. Frelin C. G. Hugues M. Lazdunski M. Biochemistry. 1981; PubMed Scopus (111) Google Scholar). of the peptides in this it particularly interesting to their in and also in which have to of a of it sea anemones toxins K+ channels in their the these or analogs of these particularly active on this of the of the of channel toxins in sea anemone venom and comprising both Na+ channel toxins to the Na+ channels M. Frelin C. Barhanin J. A. H. G. A. Schweitz H. Vigne P. Y. Acad. Sci. 1987; Scopus Google Scholar) and K+ channel toxins to block K+ channels is to have of as as potent on and INTRODUCTIONPotassium channels have an essential role in repolarization phases of action potentials and in the fine regulation of the resting potential. Molecular cloning has recently led to the identification of a large number (over 15) of genes for voltage-sensitive, non inward-rectifier, K+ (Kv) channels (1Pongs O. Physiol. Rev. 1992; 72: S69-S88Crossref PubMed Google Scholar, 2Jan L.Y. Jan Y.N. Trends Neurosci. 1990; 13: 415-419Abstract Full Text PDF PubMed Scopus (158) Google Scholar) which, when expressed in Xenopus oocytes, generate a variety of K+ channel activities with different kinetics, voltage dependences, conductances, and regulation properties. Surprisingly, only a relatively small number of toxins active on these channels has yet been discovered(3Moczydlowski E. Lucchesi K. Ravidran A. J. Membr. Biol. 1988; 105: 95-111Crossref PubMed Scopus (184) Google Scholar, 4Meves H. Herken H. Hucho F. Handbook of Experimental Pharmacology. 102. Springer Verlag, Berlin1992: 739-774Google Scholar). They are MCD peptide from bee venom(5Bidard J.-N. Mourre C. Lazdunski M. Biochem. Biophys. Res. Commun. 1987; 143: 383-389Crossref PubMed Scopus (58) Google Scholar, 6Rehm H. Bidard J.-N. Schweitz H. Lazdunski M. Biochemistry. 1988; 27: 1827-1832Crossref PubMed Scopus (55) Google Scholar), charybdotoxin and analogs from different scorpion species (7Schweitz H. Stansfeld C.E. Bidard J.-N. Fagni L. Maes P. Lazdunski M. FEBS Lett. 1989; 250: 519-522Crossref PubMed Scopus (48) Google Scholar, 8Schweitz H. Bidard J.-N. Maes P. Lazdunski M. Biochemistry. 1989; 28: 9708-9714Crossref PubMed Scopus (39) Google Scholar, 9MacKinnon R Reinhart P.H. White M.M. Neuron. 1988; 1: 997-1001Abstract Full Text PDF PubMed Scopus (111) Google Scholar, 10Garcia M.L. Garcia-Calvo M. Hidalgo P. Lee A. MacKinnon R. Biochemistry. 1994; 33: 6834-6839Crossref PubMed Scopus (244) Google Scholar, 11Garcia-Calvo M. Leonard R.J. Novick J. Stevens S.P. Schmalhofer W. Kaczorowski G.J. Garcia M.L. J. Biol. Chem. 1993; 268: 18866-18874Abstract Full Text PDF PubMed Google Scholar, 12Possani L.D. Martin B.M. Svendsen I.B. Carlsberg Res. Commun. 1982; 47: 285-289Crossref Scopus (150) Google Scholar, 13Rogawski R.S. Krueger B.K. Collins J.H. Blaustein M.P. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: 1475-1479Crossref PubMed Scopus (92) Google Scholar, 14Grissmer S. Nguyen A.N. Aiyar J. Hanson D.C. Mather R.J. Gutman G.A. Karmilowicz M.J. Auperin D.D. Chandy K.G. Mol. Pharmacol. 1994; 45 (1227-1134)PubMed Google Scholar), β-bungarotoxin(15Schmidt R.R. Betz H. Rehm H. Biochemistry. 1988; 27: 963-967Crossref PubMed Scopus (42) Google Scholar, 16Awan K.A. Dolly J.O. Neuroscience. 1991; 40: 29-39Crossref PubMed Scopus (53) Google Scholar), and dendrotoxins from mamba venoms (3Moczydlowski E. Lucchesi K. Ravidran A. J. Membr. Biol. 1988; 105: 95-111Crossref PubMed Scopus (184) Google Scholar, 5Bidard J.-N. Mourre C. Lazdunski M. Biochem. Biophys. Res. Commun. 1987; 143: 383-389Crossref PubMed Scopus (58) Google Scholar, 17Harvey A.L. Anderson A.J. Harvey A.L. Snake Toxins. Pergamon Press, Inc., New York1991: 131-164Google Scholar, 18Rehm H. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 4919-4923Crossref PubMed Scopus (170) Google Scholar, 19Benishin C.G. Sorensen R.G. Brown W.E. Krueger B.K. Blaustein M.P. Mol. Pharmacol. 1988; 34: 152-159PubMed Google Scholar, 20Halliwell J.V. Othman I.B. Pelchen-Matthews A. Dolly J.O. Proc. Natl. Acad. Sci. U. S. A. 1986; 83: 493-497Crossref PubMed Scopus (175) Google Scholar, 21Dreyer F. Rev. Physiol. Biochem. Pharmacol. 1990; 115: 93-136Crossref PubMed Google Scholar, 22Rehm H. Eur. J. Biochem. 1991; 202: 701-713Crossref PubMed Scopus (29) Google Scholar).These different toxins only block the expression of four of the cloned Kv channels (Kv1.1, Kv1.2, and Kv1.6 for MCD peptide and dendrotoxin, Kv1.1, Kv1.2, Kv1.3, and Kv1.6 for charybdotoxin) (reviewed in (23Pongs O. Trends Pharmacol. Sci. 1992; 13: 359-365Abstract Full Text PDF PubMed Scopus (73) Google Scholar)). Binding studies using radioiodinated derivatives of these toxins have been essential for the identification, purification, and determination of the subunit structure (6Rehm H. Bidard J.-N. Schweitz H. Lazdunski M. Biochemistry. 1988; 27: 1827-1832Crossref PubMed Scopus (55) Google Scholar, 24Rehm H. Lazdunski M. Biochem. Biophys. Res. Commun. 1988; 153: 231-240Crossref PubMed Scopus (34) Google Scholar, 25Betz H. Biochemistry. 1990; 29: 3591-3599Crossref PubMed Scopus (130) Google Scholar, 26Scott V.E.S. Rettig J. Parcej D.N. Keen J.N. Findlay J.B.C. Pongs O. Dolly J.O. Proc. Natl. Acad. Sci. U. S. A. 1994; 91: 1637-1641Crossref PubMed Scopus (176) Google Scholar) of these Kv channels. These toxins have also been important for the first brain localizations of Kv channels (16Awan K.A. Dolly J.O. Neuroscience. 1991; 40: 29-39Crossref PubMed Scopus (53) Google Scholar, 27Bidard J.-N. Mourre C. Gandolfo G. Schweitz H. Widmann C. Gotessmann C. Lazdunski M. Brain Res. 1989; 495: 45-57Crossref PubMed Scopus (48) Google Scholar) and are particularly interesting inducers of long term potentiation(28Cherubini E. Ben Ari Y. Gho M. Bidard J.-N. Lazdunski M. Nature. 1987; 328: 70-73Crossref PubMed Scopus (85) Google Scholar).Sea anemones produce toxins with which they paralyze their prey. They are particularly important as sources of toxins active on voltage-dependent Na+ channel which have been essential tools for studying the structure, the mechanism, and the diversity of this channel type(29Fritz H. Brey B. Béress L. Hoppe-Seyler's Z. Physiol. Chem. 1972; 353: 19-30Crossref PubMed Scopus (68) Google Scholar, 30Béress L. Béress R. Wunderer G. FEBS Lett. 1975; 50: 311-314Crossref PubMed Google Scholar, 31Romey G. Abita J.-P. Schweitz H. Wunderer G. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1976; 73: 4055-4059Crossref PubMed Scopus (158) Google Scholar, 32Béress L. Kaul P.N. Sindermann C.J. Drugs and Food from the Sea, Myth or Reality? The University of Oklahoma Press, Norman, OK1978: 59-72Google Scholar, 33Vincent J.-P. Balerna M. Barhanin J. Fosset M. Lazdunski M. Proc. Natl. Acad. Sci. U. S. A. 1980; 77: 1646-1650Crossref PubMed Scopus (71) Google Scholar, 34Barhanin J. Hugues M. Schweitz H. Vincent J.-P. Lazdunski M. J. Biol. Chem. 1981; 256: 5764-5769Abstract Full Text PDF PubMed Google Scholar, 35Frelin C. Vigne P. Schweitz H. Lazdunski M. Mol. Pharmacol. 1984; 26: 70-74PubMed Google Scholar, 36Schweitz H. Bidard J.-N. Frelin C. Lazdunski M. F. A. Biochemistry. PubMed Scopus Google Scholar, M. Frelin C. Barhanin J. A. H. G. A. Schweitz H. Vigne P. Y. Acad. Sci. 1987; Scopus Google Scholar, R.S. 1991; 29: PubMed Scopus Google the structure, and of a of toxins from Anemonia sulcata which behave as blockers of Kv channels.