Schütter N , Barreto YC , Vardanyan V , Hornig S , Hyslop S , Marangoni S , Rodrigues-Simioni L , Pongs O , Dal Belo CA .

	Figure 1. The sensitivity of whole-cell dorsal root ganglion (DRG) potassium currents to MiDCA1. (A) Representative control and (B) MiDCA1 (1 µM)-treated current traces of DRG potassium currents evoked by 1 s voltage steps to test potentials between −30 mV and +60 mV in 15 mV increments using an EPC9 patch-clamp amplifier combined with PULSE software (HEKA Elektronik, Lambrecht, Germany). DRG neurons were superfused at a flow rate of 1 mL/min with an external solution containing (in mM): NaCl 150, KCl 5, CaCl2 2.5, MgCl2 2, HEPES 10, and D-glucose 10, adjusted to pH 7.4 with NaOH. The pipette solution was (in mM): KCl 140, CaCl2 1, MgCl2 2, EGTA 9, HEPES 10, Mg-ATP 4, and GTP (Tris salt) 0.3, adjusted to pH 7.4 with KOH. Signals were filtered at 0.2–4 kHz with low pass Bessel characteristics, amplified as required and digitized at sampling intervals between one ms and 40 ms. The program PULSEFIT (HEKA Elektronik) was used to analyze the current traces. (C) Representative DRG outward currents showing their sensitivity to MiDCA1. The toxin was applied three min prior to the recordings. The gray horizontal bar in (C) indicates the duration of MiDCA1 application during the current recording. (D) Normalized outward current amplitudes (Inorm) measured before (white diamonds—w/o) and after (black circles) the application of 1 µM MiDCA1 were plotted against test voltages. Current amplitudes recorded from MiDCA1-sensitive neurons before and three min after MiDCA1 application as shown in (C) were subtracted from each other to obtain information about the MiDCA1-sensitive current. The points represent the mean ± SEM (n = 19). All measurements were done at 37 °C. Vertical and horizontal scale bars in (A–C) indicate current amplitude and pulse duration, respectively.
	Figure 2. Comparison of the inhibitory activity of MiDCA1 and guangxitoxin (GxTx) on DRG potassium currents. (A) Representative recordings of DRG potassium currents after application of 1 µM MiDCA1 (gray horizontal bar) and subsequent application of 30 nM GxTx (black horizontal bar). (B) Representative recordings of DRG potassium currents after application of 1 µM MiDCA1 (gray horizontal bar) preceded by application of 30 nM GxTx (black horizontal bar). Currents were elicited by a 1 s voltage step to +60 mV from a holding potential of −30 mV. Toxins were applied three min prior to the recordings. All measurements were done at 37 °C. (C) Data were acquired using the experimental design shown in (A,B). Relative current inhibition was obtained by dividing plateau current amplitudes, recorded after toxin application at the end of a 1 s test pulse to +60 mV, by the current amplitude recorded before application. White rectangles represent the data for toxin-sensitive DRG neurons; black rectangles represent those of DRG-insensitive neurons. (D) Relative current inhibition, calculated as in (C), measured after MiDCA1 application followed by GxTx application (1st MiDCA1, 2nd GxTx—black rectangles) or after GxTx application followed by MiDCA1 application (1st GxTx, 2nd MiDCA1—gray rectangles). (E) Outward current amplitudes measured before (black diamonds—Control) and after the application of 1 μM MiDCA (gray rectangles), 30 nM GxTx (black triangles), and 120 nM GxTx (white circles) plotted against the test voltages. Note that the response to 120 nM GxTx was virtually identical to that seen with 30 nM GxTx. The results in panels (C,D) are shown as the mean ± SEM (n = 7). n.s. not significant (panels C and D).
	Figure 3. Inhibition of Kv2.1 channels by MiDCA1. (A) Representative current traces of the Kv2.1 channel recorded from Xenopus oocytes before (control), during incubation with 1 μM MiDCA1, and during washout (wash). The current traces correspond to the points shown in (B) as open circles. (B) Normalized current amplitude before (control), during application of 1 µM MiDCA1 (horizontal bar), and during washout (wash). Inhibition of current was calculated as the difference between the first and second open circles (0.55 ± 0.089, n = 3, p < 0.001). (C) Typical current traces from several types of Kv channels expressed in oocytes and screened for inhibition by MiDCA1. Symbols are identical to those in (A). Oocytes were transfected with the Kv channels as described in the Methods, and at least three cells were tested for each channel type, with no significant differences in the responses within each set of cells. None of the channel types screened was sensitive to blockade by MiDCA1, except for Kv2.1 (panels A and B).

Alabi, Portability of paddle motif function and pharmacology in voltage sensors. 2007, Pubmed, Xenbase

Alabi, Portability of paddle motif function and pharmacology in voltage sensors. 2007, Pubmed , Xenbase
Belo, Pharmacological and structural characterization of a novel phospholipase A2 from Micrurus dumerilii carinicauda venom. 2005, Pubmed
Belo, Determination of the amino acid sequence of a new phospholipase A(2) (MIDCA1) isolated from Micrurus dumerilii carinicauda venom. 2005, Pubmed
Bocksteins, Kv2.1 and silent Kv subunits underlie the delayed rectifier K+ current in cultured small mouse DRG neurons. 2009, Pubmed
Bocksteins, The electrically silent Kv6.4 subunit confers hyperpolarized gating charge movement in Kv2.1/Kv6.4 heterotetrameric channels. 2012, Pubmed
Bradford, A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. 1976, Pubmed
Chen, Isolation and characterization of SsmTx-I, a Specific Kv2.1 blocker from the venom of the centipede Scolopendra Subspinipes Mutilans L. Koch. 2014, Pubmed
Davletov, Regulation of SNARE fusion machinery by fatty acids. 2007, Pubmed
Dreyer, The actions of presynaptic snake toxins on membrane currents of mouse motor nerve terminals. 1987, Pubmed
Feinshreiber, Non-conducting function of the Kv2.1 channel enables it to recruit vesicles for release in neuroendocrine and nerve cells. 2010, Pubmed
Flink, Iberiotoxin-induced block of Ca2+-activated K+ channels induces dihydropyridine sensitivity of ACh release from mammalian motor nerve terminals. 2003, Pubmed
Harris, Secreted phospholipases A2 of snake venoms: effects on the peripheral neuromuscular system with comments on the role of phospholipases A2 in disorders of the CNS and their uses in industry. 2013, Pubmed
Herrington, Blockers of the delayed-rectifier potassium current in pancreatic beta-cells enhance glucose-dependent insulin secretion. 2006, Pubmed
Johnston, Going native: voltage-gated potassium channels controlling neuronal excitability. 2010, Pubmed
Ma, Characterization of a novel Long QT syndrome mutation G52R-KCNE1 in a Chinese family. 2003, Pubmed , Xenbase
MacKinnon, Mutant potassium channels with altered binding of charybdotoxin, a pore-blocking peptide inhibitor. 1989, Pubmed , Xenbase
Mouhat, Diversity of folds in animal toxins acting on ion channels. 2004, Pubmed
Pelchen-Matthews, Distribution in the rat central nervous system of acceptor sub-types for dendrotoxin, a K+ channel probe. 1989, Pubmed
Poling, Time- and voltage-dependent block of delayed rectifier potassium channels by docosahexaenoic acid. 1995, Pubmed
Pongs, Ancillary subunits associated with voltage-dependent K+ channels. 2010, Pubmed
Quinn, Pharmacology and surface electrostatics of the K channel outer pore vestibule. 2006, Pubmed , Xenbase
Ramu, Enzymatic activation of voltage-gated potassium channels. 2006, Pubmed
Rehm, Molecular aspects of neuronal voltage-dependent K+ channels. 1991, Pubmed
Rigoni, Equivalent effects of snake PLA2 neurotoxins and lysophospholipid-fatty acid mixtures. 2005, Pubmed
Rowan, Potassium channel blocking actions of beta-bungarotoxin and related toxins on mouse and frog motor nerve terminals. 1988, Pubmed
Stocker, Subunit assembly and domain analysis of electrically silent K+ channel alpha-subunits of the rat Kv9 subfamily. 1999, Pubmed , Xenbase
Stocker, An apamin-sensitive Ca2+-activated K+ current in hippocampal pyramidal neurons. 1999, Pubmed
Swartz, Tarantula toxins interacting with voltage sensors in potassium channels. 2007, Pubmed
Takeda, Potassium channels as a potential therapeutic target for trigeminal neuropathic and inflammatory pain. 2011, Pubmed
Tsantoulas, Kv2 dysfunction after peripheral axotomy enhances sensory neuron responsiveness to sustained input. 2014, Pubmed
Vacher, Regulation of Kv1 channel trafficking by the mamba snake neurotoxin dendrotoxin K. 2007, Pubmed
Xiao, Snake Venom PLA2, a Promising Target for Broad-Spectrum Antivenom Drug Development. 2017, Pubmed
Zhu, Structural and functional characterization of Kv6.2 a new gamma-subunit of voltage-gated potassium channel. 1999, Pubmed
Zoga, KATP channel subunits in rat dorsal root ganglia: alterations by painful axotomy. 2010, Pubmed