- Alomone Labs Tertiapin-Q-ATTO Fluor-488 inhibits Kir3.2 channels heterologously expressed in Xenopus oocytes.A continuous current trace recorded at a holding potential of -80 mV. Kir3.2 currents are downward reflections activated by high K+ containing solution. While activated, 50 nM and 100 nM of Tertiapin-Q-ATTO Fluor-488 (#STT-170-AG) were applied for 2 min (indicated as bars).
- Alomone Labs Tertiapin-Q-ATTO Fluor-488 binds GIRK1/4-Cherry transfected HEK293T cells.Transfected cells were incubated in the presence of 200 nM Tertiapin-Q-ATTO Fluor-488 (#STT-170-AG). The labeled toxin accumulates on the membrane surface after 26 sec. No binding is achieved in untransfected cells (data not shown).
The pictures are a kind gift from the lab of Prof. Eithan Reuveny, Weizmann Institute, Israel.
Tertiapin, the native toxin, was originally isolated from European honey bee Apis mellifera venom. Native and synthetic Tertiapin blocks a range of inward rectifier K+ channels (Kir), in particular ROMK1 (Kir1.1, IC50 = 2 nM) and GIRK (Kir3 family, IC50 for the Kir3.1/3.4 heteromer was 8.6 nM) but with no effect on the Kir2 family member1. In accordance, it was shown to inhibit acetylcholine induced K+ currents in mammalian cardiomyocytes2,3.
Tertiapin-Q is a derivative of Tertiapin in which Met13 is substituted by a Gln residue. However, unlike native Tertiapin, Tertiapin-Q is non-oxidizable and therefore is more stable4.
Tertiapin-Q inhibits the above-mentioned channels with similar affinities and also inhibits Ca2-activated large conductance BK-type K+ channels in a concentration and voltage-dependent manner5.
Double staining of GIRK2 channels in substantia nigra pars compacta using Tertiapin-Q-ATTO Fluor-488 and Guinea pig Anti-GIRK2 (Kir3.2) Antibody.Rat brain sections were first incubated with 33 nM Tertiapin-Q-ATTO Fluor-488 (#STT-170-AG), (green). The same sections were incubated with Guinea pig Anti-GIRK2 (Kir3.2) Antibody (#APC-006-GP). A. Tertiapin-Q-ATTO Fluor-488 binding appears in profiles of substantia nigra pars compacta (SNC) neurons (arrows). B. GIRK2 staining (red) is detected in profiles of SNC neurons (arrows). C. Merge of the two images demonstrates co-staining of GIRK2 channels by Tertiapin-Q-ATTO Fluor-488 and by Guinea pig Anti-GIRK2 (Kir3.2) Antibody. DAPI staining (blue) is used to stain nuclei.