Synthetic charybdotoxin-iberiotoxin chimeric peptides define toxin binding sites on calcium-activated and voltage-dependent potassium channels

Giangiacomo, Kathleen M.; Sugg, Elizabeth E.; García‐Calvo, Margarita; Leonard, Reid J.; McManus, Owen B.; Kaczorowski, Gregory J.; García, María L.

doi:10.1021/bi00060a030

Cited by 82 publications

(52 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1D). The k on value of 9.55 ϫ 10 7 M Ϫ1 s Ϫ1 determined with this relationship is higher than typical values reported for peptide-channel interactions (Park and Miller, 1992a,b;Giangiacomo et al, 1993;Mullmann et al, 1999) but is similar to the values determined for the ShK toxin (Middleton et al, 2003) and Pi2 (Péter et al, 2001), with picomolar affinities for Kv1.3.…”

Section: Discussionsupporting

confidence: 69%

Vm24, a Natural Immunosuppressive Peptide, Potently and Selectively Blocks Kv1.3 Potassium Channels of Human T Cells

et al. 2012

View full text Add to dashboard Cite

Blockade of Kv1.3 K ϩ channels in T cells is a promising therapeutic approach for the treatment of autoimmune diseases such as multiple sclerosis and type 1 diabetes mellitus. Vm24 (␣-KTx 23.1) is a novel 36-residue Kv1.3-specific peptide isolated from the venom of the scorpion Vaejovis mexicanus smithi. Vm24 inhibits Kv1.3 channels of human lymphocytes with high affinity (K d ϭ 2.9 pM) and exhibits Ͼ1500-fold selectivity over other ion channels assayed. It inhibits the proliferation and Ca 2ϩ signaling of human T cells in vitro and reduces delayed-type hypersensitivity reactions in rats in vivo. Our results indicate that Vm24 has exceptional pharmacological properties that make it an excellent candidate for treatment of certain autoimmune diseases.

show abstract

Section: Discussionsupporting

confidence: 69%

Vm24, a Natural Immunosuppressive Peptide, Potently and Selectively Blocks Kv1.3 Potassium Channels of Human T Cells

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Although ChTX was initially regarded as a specific blocker of the large conductance Ca2+ -dependent K+ channels (Miller et al, 1985), it has recently been shown that some cloned, voltage-gated K+ channels are also very sensitive to ChTX (Stuhmer et al, 1989;Grissmer et al, 1994). As we have shown, however, the major current observed in these cells was also sensitive to IbTX, an agent which does not affect voltagegated channels (Galvez et al, 1990;Giangiacomo et al, 1993).…”

Section: Discussionmentioning

confidence: 62%

Potassium currents in human freshly isolated bronchial smooth muscle cells

Snetkov¹,

Hirst²,

Twort³

et al. 1995

British J Pharmacology

View full text Add to dashboard Cite

1 K+ currents were studied in smooth muscle cells enzymatically dissociated from human bronchi, by use of the patch-clamp technique. 2 In whole-cell recordings a depolarization-induced, 4-aminopyridine (4-AP)-sensitive current was observed in only 26 of 155 cells, and in 20 of these 26 cells its amplitude at a test potential of 0 mV was less than 100 pA. 3 In the majority of cells depolarization to -40 mV or more positive potentials induced a noisy outward current which activated within milliseconds and showed almost no inactivation even during a 5 s depolarizing voltage step. This current was insensitive to 4-AP (up to 5 mM) but was strongly inhibited in the presence of tetraethylammonium (TEA, 1 mM), charybdotoxin (ChTX, 100 nM) or iberiotoxin (IbTX, 50 nM) in the bath. The same current was also recorded by the nystatin-perforated patch technique. 4 Single channels with a conductance of about 210 pS were recorded in cell-attached patch, inside-out patch, outside-out patch and whole-cell recording configurations. Channel open state probability in inside-out patches was 0.5 at a membrane potential of 4+14 mV (mean+ s.d., n = 13) mV even with a free Ca2+ concentration on the cytosolic side of the patch of less than 0.1 nM. Open state probability increased with depolarization and internal Ca2+ concentration. Single channels could be reversibly blocked by externally applied TEA, ChTX and IbTX. 5 In current-clamp recordings with 100 nm free Ca2+ in the intracellular solution both TEA and ChTX caused substantial concentration-dependent depolarization. 6 These results suggest that in human bronchial smooth muscle cells, in marked contrast to other species, the majority of the outward current induced by depolarization is not due to a delayed rectifier, but to the activity of a large conductance, ChTX-sensitive K+ channel. The Ca2+-and voltagedependency of this channel may well allow a sufficiently high open state probability for it to play a part in the regulation of the resting membrane potential.

show abstract

“…3B) Target sizes are mean ± SEM from independent determinations made using either three (t) or four (*) different smooth muscle sarcolemmal membrane preparations. Table 1. dependent K+ channel, K,1.3, in neuronal tissue and lymphocytes (19,(24)(25)(26). For example, it has been shown with rat brain synaptosomal membranes that I251-ChTX binds to a single class of sites which display the pharmacological properties characteristic of the K,1.3 channel (19).…”

Section: Resultsmentioning

confidence: 99%

Functional unit size of the charybdotoxin receptor in smooth muscle.

García‐Calvo¹,

Knaus²,

García³

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Target inactivation analysis was used to determine the functional size of the charybdotoxin (ChTX) receptor in aortic and tracheal sarcolemmal membrane vesicles. This receptor has previously been shown to be an integral component of the high-conductance Ca2+-activated K+ (Maxi-K) channel in these smooth muscles. Exposure of either bovine aortic or bovine tracheal sarcolemma to high-energy irradiation results in disappearance of 125I-labeled ChTX binding activity as a monoexponential function of radiation dose; from these functions molecular masses of 88 ± 10 kDa and 89 ± 6 kDa, respectively, can be calculated. Similar results were obtained from radiation inactivation studies with the detergentsolubilized ChTX receptor from aortic sarcolemmal membranes. The effect of radiation on '7I-labeled ChTX binding is to decrease the number of functional ChTX receptors without affecting the affinity of receptors for the toxin, indicating that radiation is destroying, rather than altering, the binding site. The validity of the radiation inactivation technique in these membrane preparations is supported by data obtained in parallel experiments in which target sizes of the a, subunit of the L-type Ca2+ channel and 5'-nucleotidase were measured.

show abstract

Synthetic charybdotoxin-iberiotoxin chimeric peptides define toxin binding sites on calcium-activated and voltage-dependent potassium channels

Cited by 82 publications

References 30 publications

Vm24, a Natural Immunosuppressive Peptide, Potently and Selectively Blocks Kv1.3 Potassium Channels of Human T Cells

Vm24, a Natural Immunosuppressive Peptide, Potently and Selectively Blocks Kv1.3 Potassium Channels of Human T Cells

Potassium currents in human freshly isolated bronchial smooth muscle cells

Functional unit size of the charybdotoxin receptor in smooth muscle.

Contact Info

Product

Resources

About