Tertiapin Q

Tertiapin has been isolated from the venom of the Honeybee Apis mellifera. Tertiapin-Q is an oxidation-resistant mutant of the wild-type tertiapin where Methionine 13 has been replaced by a Glutamine. Tertiapin-Q blocks the inwardly rectifying Kir1.1 (ROMK1) and Kir3.1/3.4 (GIRK1/GIRK4 also known as IKACh) potassium channels with Kd values of around 2 nM and 8 nM respectively.Tertiapin-Q also inhibits calcium-activated large conductance BK potassium channels (KCa1.1) in a concentration and voltage-dependent manner (IC50 ~ 5 nM), in addition to inhibiting Kir3.1/3.2 (GIRK1/GIRK2) heteromultimer potassium channels with a Kd close to 270 nM. Tertiapin-Q can prevent dose-dependent acetylcholine (ACh) -induced atrioventricular blocks in mammalian hearts, as KCNJ3/KCNJ5 channels (also named I (KACh) ), are activated by ACh found in mammalian myocytes.