Screen Quest™ No Wash Potassium Channel Assay Kit

Screen Quest™ No Wash Potassium Channel Assay Kit is a fluorescence-based kit for assessing potassium channel activity through thallium influx in cell-based microplate assays.

Functional channel readout: Converts channel-mediated thallium influx into an increase in fluorescence for assessing potassium channel activity
Cell-permeable indicator: Intracellular esterases cleave the AM groups to generate a charged, thallium-responsive indicator
No-wash microplate format: Supports 96-well and 384-well assays with kinetic fluorescence detection at recommended Ex/Em settings of 490/525 nm
Research applications: Suitable for functional potassium channel studies and screening channel inhibitors or activators

Astemizole dose dependent inhibition of hERG channel was measured in HEK293-KCNH2 cells with Screen Quest™ Potassium Ion Channel Kit. The cells were seeded overnight at 20,000 cells/100 µL/well in a Costar black wall/clear bottom 96-well poly-D-lysine plate. The cells were incubated with 100 µL of dye-loading solution for 1 hour at 37°C. 10 µL of Astemizole was added to the cells and incubated for 30 minutes at 37°C. 50 µL of 0.5 mM Tl2SO4 and 2.5 mM K2SO4 containing stimulus solution was injected in each well by FlexStation and read every sec for 3 minutes at excitation/emission=490/525nm. IC50 = 0.46 µM.

Protocol

COA

Catalog	Size	Price
36550	1 Plate	Price
36551	10 Plates	Price
36552	100 Plates	Price

Overview

Potassium (K+) ion channel plays an important role in regulating fundamental biological processes including heart rate, hormone and neurotransmitter secretion, water and electrolyte balance. Potassium ion channel has been considered as drug targets for disease indications including arrhythmia, pain, diabetes, neurological dysfunctions etc. The permeability of Tl+ through K+ channel has been widely used to assay K+ channel. The cells that express K+ channel of interests (e.g. hERG, Kv1.3, Kir2.1, KATP) are pre-loaded with a Tl+ sensitive dye. The dye is non-fluorescent and is permeable to cell membrane. Once inside the cell, the non-fluorescent AM ester dye is cleaved by endogenous esterase into a negatively charges dye that stays inside cells. When a stimulus buffer containing low dose of Tl+ is added to cells, the Tl+ flows across the K+ channel and binds to Tl+ sensitive dye, generating a fluorescent signal. This signal is proportional to the activity of K+ channel. If an antagonist or antagonist is added to the cells, the fluorescent signal decreases or increases respectively, to reflect the inhibited or stimulated activity of K+ channel.

Components

Catalog 36550 (1 Plate)

Component A: Tl-520 AM	1 vial
Component B: 10X Pluronic® F127 Plus	1 bottle (1 mL)
Component C: HHBS (Hanks with 20 mM Hepes)	1 bottle (9 mL)
Component D: 5X Chloride-free Assay Buffer	1 bottle (2 mL)
Component E: K2SO4 (250 mM)	1 bottle (2 mL)
Component F: Tl2SO4	Not Provided (Sigma Cat#: 208191)

Catalog 36551 (10 Plates)

Component A: Tl-520 AM	1 vial
Component B: 10X Pluronic® F127 Plus	1 bottle (10 mL)
Component C: HHBS (Hanks with 20 mM Hepes)	1 bottle (100 mL)
Component D: 5X Chloride-free Assay Buffer	1 bottle (20 mL)
Component E: K2SO4 (250 mM)	1 bottle (2 mL)
Component F: Tl2SO4	Not Provided (Sigma Cat#: 208191)

Catalog 36552 (100 Plates)

Component A: Tl-520 AM	10 vials
Component B: 10X Pluronic® F127 Plus	1 bottle (10 mL)
Component C: HHBS (Hanks with 20 mM Hepes)	Not Included
Component D: 5X Chloride-free Assay Buffer	2 bottles (100 mL/bottle)
Component E: K2SO4 (250 mM)	2 bottles (100 mL/bottle)
Component F: Tl2SO4	Not Provided (Sigma Cat#: 208191)

Spectral properties

Excitation (nm)	494
Emission (nm)	516

Usage and storage

Intended use

Research Use Only (RUO)

Instrument settings

Fluorescence microplate reader
Excitation	490 nm
Emission	525 nm
Cutoff	515 nm
Recommended plate	Black wall/clear bottom
Instrument specification(s)	Bottom read mode/Programmable liquid handling

Other instruments	ArrayScan, FDSS, FLIPR, FlexStation, IN Cell Analyzer, NOVOStar, ViewLux

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Page updated on October 4, 2026