Measurement of Ion Channel Surface Density

Creative Bioarray is committed to establishing a variety of experimental schemes to help clients measure the surface density of ion channels. We aim to provide our clients with high-satisfaction scientific services and technical support in ion channel analysis.

Background

The life cycle of surface ion channels generally includes their synthesis and assembly in the endoplasmic reticulum (ER) membrane and post-transport modification in the Golgi apparatus. Mature channels are transported to the plasma membrane from where it is removed by endocytosis and either recycled back to the cell surface or trafficked to lysosomes for degradation. Thus, at any moment in a cell, a specific ion channel is distributed among different compartments, with only a small fraction of the total channels present on the cell surface. Given that functional currents are generated by surface channels, it is necessary to measure the proportion of total channels on the cell surface.

Changes in the surface density of ion channels often lead to loss- or gain-of-function mutations in ion channels which cause severe diseases. Therefore, understanding the ratio of the total channel on the cell surface and analyzing how it changes under different conditions is critical to further understanding the pathogenesis of related diseases and developing potential treatments.

Fig. 1 Lifecycle of an ion channel. (Morgenstern, 2021)

Our Services

In order to provide our clients with the service of measuring or estimating the number of channels on the cell surface, our research team has established a variety of strategies to meet their different scientific needs. Our services and strategies include but not limited to:

• We calculated the number of certain voltage-gated ion channels in the plasma membrane by measuring the maximum gate charge (Qmax). The method is applicable to ion channels containing voltage sensors that generate measurable gated currents.
• We help clients study endogenous channels in native tissues through surface biotinylation, which involves treating cells with a non-permeable biotinylation reaction mixture to non-selectively attach biotin groups to all surface proteins and detect channel proteins of interest by gel electrophoresis and Western blotting. This strategy is applicable in the case of low throughput and the availability of quality antibodies for the channel of interest.
• We examined surface ion channels by combining fluorescently labeled proteins with confocal or total internal reflection fluorescence (TIRF) imaging.
• We selectively label surface populations of channels of interest by introducing high-affinity, fluorescently-conjugated exogenous epitope tags into extracellular regions of ion channels. We have a variety of epitope tags available, such as the 13-residue peptide of the α-bungarotoxin binding site (BBS) derived from the nicotinic acetylcholine receptor and myc tags. We have successfully applied these tags and flow cytometry to help clients monitor the surface expression of various channels, such as Ca_V1.2, Ca_V1.2, hERG, KCNQ1, and CFTR.

Advantages

• Unparalleled expertise and advanced technology platform
• Diverse solutions tailored to your needs
• Short turnaround time and cost-effectiveness

Creative Bioarray has extensive expertise and rich experience in the measurement of ion channel surface density. Our expertise provides a range of flexible solutions to meet your specific requirements and fit your budget. If you are interested in our services, please feel free to contact us.

Reference

1. Morgenstern, T. J.; Colecraft, H. M. Controlling ion channel trafficking by targeted ubiquitination and deubiquitination//Methods in Enzymology. Academic Press, 2021, 654: 139-167.