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Origin Synthetic peptide
MW: 2452 Da
Purity: >98% (HPLC)
Effective concentration 2-200 nM.
Sequence ALCNCNRIIIPHQCWKKCGKK.
Modifications Disulfide bonds between Cys3-Cys14, Cys5-Cys18. Lys21 - C-terminal amidation.
Structure
Sold under license from the University of Pennsylvania.
Molecular formula C106H175N35O24S4.
CAS No.: 910044-56-3
Activity Tertiapin-Q blocks a range of inward rectifier K+ channels (Kir), in particular ROMK1 and GIRK, but with no effect on Kir2 family members1. In addition, it was shown to inhibit acetylcholine induced K+ currents in heart2,3. Tertiapin-Q is a derivative of Tertiapin in which Met13 is replaced by Gln. Tertiapin-Q inhibits the above-mentioned channels with similar affinities4.
Shipping and storage Shipped at room temperature. Product as supplied can be stored intact at room temperature for several weeks. For longer periods, it should be stored at -20°C.
Solubility Any aqueous buffer. Centrifuge all product preparations before use (10000 x g 5 min).
Storage of solutions Up to one week at 4°C or three months at -20°C.
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, increasing concentrations of Tertiapin-Q (#STT-170) were applied (arrows at the bottom of the trace).
Alomone Labs Tertiapin-Q blocks Kir1.1 channels expressed in Xenopus oocytes.
Representative time course of Kir1.1 current, stimulated by a continuous application (top dotted line) of high K+ concentration, and reversible inhibition by 5 nM and 50 nM Tertiapin-Q (#STT-170), as indicated (horizontal bar), at a holding potential of -80 mV.
Kanjhan, R.et al. (2005) J. Pharmacol. Exp. Ther.314, 1353.
Scientific background
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.
Image & Title Alomone Labs Tertiapin-Q blocks time-dependent hyperpolarization-activated current (IKH) in rat atrial cardiomyocytes.Whole-cell voltage-clamp was performed on neonatal rat atrial cardiomyocyte (NRAM) primary cultures. A. The voltage-clamp recordings depict large inward currents evoked by hyperpolarizations (5 sec), whereas, very little current is activated during steps to -50 mV and more positive potentials. Na+ current (INa) and T-type Ca2+ current (ICaT) are inactivated by holding the cells at the potential of -40 mV. B. In the presence of Tertiapin-Q (#STT-170) (100 nM), which selectively suppresses the constitutively active acetylcholine (ACh)-mediated K+ current IKACh-c component of IKH, only inward rectifier current (IK1) is left with K+ leak.Adapted from Majumder, R.et al. (2016) PLoS Comput. Biol.12, e1004946. with permission of PLoS.
Last update: 11/04/2021
Tertiapin-Q (#STT-170) is a highly pure, synthetic, and biologically active peptide toxin.
Li+ modulates GIRK activity in hippocampal neurons.
Incubation of neurons with 1 mM Li+ increased Ibasal in low-K+ solution. Ibasal was measured at −120 mV (voltage step from the holding potential of −60 mV) to enhance the sensitivity of measurement. Representative traces recorded in the low-K+ solution before (black) and after (pink) application of Tertiapin-Q (#STT-170). Adapted from Farhy Tselnicker, I.et al. (2014) with permission of Proceedings of the National Academy of Sciences.
Bioassay Tested
Alomone Labs Tertiapin-Q inhibits Kir3.2 channel 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, increasing concentrations of Tertiapin-Q (#STT-170) were applied (arrows at the bottom of the trace).
Alomone Labs Tertiapin-Q blocks Kir1.1 channels expressed in Xenopus oocytes.Representative time course of Kir1.1 current, stimulated by a continuous application (top dotted line) of high K+ concentration, and reversible inhibition by 5 nM and 50 nM Tertiapin-Q (#STT-170), as indicated (horizontal bar), at a holding potential of -80 mV.
Li+ modulates GIRK activity in hippocampal neurons.Incubation of neurons with 1 mM Li+ increased Ibasal in low-K+ solution. Ibasal was measured at −120 mV (voltage step from the holding potential of −60 mV) to enhance the sensitivity of measurement. Representative traces recorded in the low-K+ solution before (black) and after (pink) application of Tertiapin-Q (#STT-170).