Lq2

Lq2 is also known as Potassium channel toxin alpha-KTx 1.2, Charybdotoxin-2, ChTX-Lq2, ChTx-d, Toxin 18-2 or Lqh 18-2.

The name Lq2 refers to the name of the animal species in which the toxin can be found.^[2] Lq2 can be found in the scorpion Leiurus quinquestriatus (Lq).^[3][4] Lq2 is structurally similar to Lq1, which had been found previously and which is also a potassium channel blocker.

Lq2 is a component of the venom of the scorpion Leiurus quinquestriatus, known under various names, for example the deathstalker, the Israeli desert scorpion or the yellow scorpion.

Lq2 is a small peptide of 37 amino acids. Lq2 contains the classical scorpion toxin alpha-beta scaffold and is structurally similar to the neurotoxin Charybdotoxin (CTX).^[5] Lq2 consists of an α-helix and a β-sheet, connected by an αβ3 loop containing disulfide bridges. The proteins three-dimensional structure has been reconstructed using nuclear magnetic resonance techniques.^[5]

Lq2 interacts with all three types of potassium channels:^[6] the voltage-activated, the Ca²⁺- activated and the inward-rectifier potassium channels.^[7] The unique trait of Lq2 is its high affinity for certain inward-rectifier potassium ion channels, especially the Renal Outer Medullary Potassium channel ROMK1. This ion channel contributes to the regulation of the resting membrane potential.