- Peptide (C)SNQLQSSEDEPAFVSK, corresponding to amino acid residues 454-469 of rat KV4.2 (Accession Q63881). Intracellular, C-terminus.
- Mouse and rat brain frozen sections, (1:60).
- Expression of KV4.2 in substantia nigraImmunohistochemical staining of perfusion-fixed frozen mouse and rat brain sections using Anti-KV4.2-ATTO Fluor-633 Antibody (#APC-023-FR), (1:60). A. Mouse brain. B. Rat brain. KV4.2 staining (magenta) in both sections is detected in cells with neuronal outline (arrows). DAPI is used as the counterstain (blue).
KV4.2 possesses the signature structure of the voltage-dependent K+ channels: six membrane-spanning domains with intracellular N and C termini. As with other members of the voltage-gated K+ channel superfamily, the functional channel is a tetramer that can be composed of more than one member of the Shal subfamily, i.e. heterotetramers of KV4.1 and KV4.3.
The KV4 channels are characterized by activation at subthreshold membrane potentials, inactivate rapidly and recover from inactivation quickly compared with other voltage-dependent K+ channels. This type of current is known as transient A-type K+ currents. For example, depolarization-activated K+ currents in rat neostriatal cholinergic interneurons are predominantly of the A-type and attributable to coexpression of KV4.2 and KV4.1 subunits.2
The biophysical properties of the KV4.2 subunit can be modified by its association with auxiliary β subunits such as the KChIP family that increase KV4.2 current densities and accelerates both the inactivation and the recovery time.
KV4.2 is also highly expressed in the heart where together with KV4.3 underlie the fast inactivating and recovering cardiac transient outward current Ito.3
Several toxins from spider venoms are potent blockers (affecting the channels in the nanomolar range) of KV4.2 channels. Among these the most potent and selective are Stromatoxin-1 (#STS-350), (1.2nM), Phrixotoxin-1 (#STP-700), (5 nM), Phrixotoxin-2 (#STP-710), (34 nM) and Heteropodatoxin-2 (#STH-340), (100 nM).4