- Peptide DTSGHFHDSGVGDLDEDPKC, corresponding to amino acid residues 2-21 of human KCNN3 (Accession Q9UGI6). Intracellular, N-terminus.
- Expression of KCa2.3 (SK3) in rat brainImmunohistochemical staining of rat brain perfusion-fixed frozen sections using Anti-KCNN3 (KCa2.3, SK3) (N-term)-ATTO Fluor-594 Antibody (#APC-025-AR). A. SK3 channel (red) is visualized in the rat substantia nigra pars compacta. B. Pre-incubation of the Anti-KCNN3 (KCa2.3, SK3) (N-term)-ATTO Fluor-594 Antibody with the immunogen peptide, blocks specific staining. DAPI Nissl is used as the counterstain (blue).
- Mouse CCDcl1 cells (1:100) (Li, Y. et al. (2016) PLoS ONE 11, e0155006.).
KCa2.3 (KCNN3, SK3) is a member of the Ca2+-activated K+ channel family with small conductance that includes KCa2.1 (KCNN1, SK1) and KCa2.2 (KCNN2, SK2). The channel is voltage insensitive and is activated by intracellular Ca2+ in the submicromolar range. It has, though, a similar topology to that of voltage-dependent K+ channels (KV channels), that is six transmembrane domains and intracellular N- and C-termini. The functional channel of all the KCa2 family members is a multimeric protein composed of four pore-forming subunits.
KCa2 channels are extremely sensitive to the levels of intracellular Ca2+ and concentrations as low as 300-700 nM can open the channels very rapidly (5-15 ms). Hence, the KCa2 channels are highly sensitive and fast Ca2+ sensors resembling other known Ca2+-binding proteins. This type of Ca2+-dependent activation is achieved by the constitutive binding of the KCa2 channels to calmodulin, a highly expressed Ca2+-binding protein via a calmodulin-binding domain situated at the cytoplasmic C-terminus.
Pharmacologically, the KCa2 channels are the only known targets of the bee venom toxin Apamin, with KCa2.1 being the least sensitive, KCa2.2 the most sensitive and KCa2.3 showing intermediate sensitivity.
KCa2.3 is predominantly expressed in the nervous system although expression in endothelial cells, heart and liver have been described.
KCa2.3 is known to be involved in the regulation of neuronal excitability. They do so mainly via a phenomenon known as after hyperpolarization in which KCa2 channels open in response to increased intracellular Ca2+ concentrations that result from the entry of extracellular Ca2+ through voltage-dependent Ca2+ channels during action potentials. In this way, KCa2 channels effectively form a Ca2+-mediated feedback loop.
KCa2.3 is involved in the control of firing rate and subsequent dopamine secretion from midbrain dopaminergic neurons. Since malfunction of these neurons is involved in several pathological disorders such as Parkinson’s disease and Schizophrenia, modulators of the KCa2.3 channels have been proposed to be of therapeutic value in these diseases.
Species reactivity key:
Expression of KCa2.3 (SK3) in mouse mCCDcl1 cells.Immunocytochemical staining of mouse mCCDcl1 cells using Anti-KCNN3 (KCa2.3, SK3) (N-term)-ATTO Fluor-594 Antibody (#APC-025-AR). SK3 channel is detected on the cell surface. Preincubating the antibody with the control peptide antigen (right panels) demonstrates the specificity of the antibody. DAPI (blue) is used to stain nuclei.Adapted from Li, Y. et al. (2016) PLoS ONE 11, e0155006. with permission of PLoS.
Anti-KCNN3 (KCa2.3, SK3) (N-term) Antibody (#APC-025) is a highly specific antibody directed against an epitope of the human protein. The antibody can be used in western blot, immunocytochemistry, and immunohistochemistry applications. It has been designed to recognize KCNN3 from human, rat, and mouse samples.
Anti-KCNN3 (KCa2.3, SK3) (N-term)-ATTO Fluor-594 Antibody (#APC-025-AR) is directly labeled with an ATTO-594 fluorescent dye. ATTO dyes are characterized by strong absorption (high extinction coefficient), high fluorescence quantum yield, and high photo-stability. The ATTO-594 fluorescent label belongs to the class of Rhodamine dyes and can be used with fluorescent equipment typically optimized to detect Texas Red and Alexa-594. Anti-KCNN3 (KCa2.3, SK3) (N-term)-ATTO Fluor-594 Antibody is specially suited to experiments requiring simultaneous labeling of different markers.
- Mouse kidney sections (1:200).
Li, Y. et al. (2016) PLoS ONE 11, e0155006.
- Mouse CCDcl1 cells (1:100).
Li, Y. et al. (2016) PLoS ONE 11, e0155006.
- Rat DRGs.
Jager, S.B. et al. (2018) J. Neurosci. Methods 297, 1.