KCNN3
Description
The KCNN3 (potassium calcium-activated channel subfamily N member 3) is a protein-coding gene located on chromosome 1.
The KCNN3 gene encodes the small conductance calcium-activated potassium channel 3 (SK3), also known as KCa2.3, a protein responsible for the calcium-dependent after hyperpolarisation current (IAHP). It belongs to a family of small-conductance potassium channels with three members - SK1, SK2, and SK3 - sharing 60-70% sequence identity. The channels are responsible for the medium and possibly the slow components of the IAHP. The KCa2.3 protein consists of 6 transmembrane domains, a pore-forming region, and intracellular N- and C- termini. It is readily blocked by apamin. The KCNN3 gene is located on chromosome 1q21. KCa2.3 is expressed in various tissues, including the central nervous system, muscle, liver, pituitary, prostate, kidney, pancreas, and vascular endothelium. Notably, it is most abundant in the brain and is also found in peripheral tissues rich in smooth muscle. The expression level of KCNN3 is regulated by hormones, particularly estrogen, which enhances transcription of the KCNN3 gene and affects the activity of KCa2.3 channels on the cell membrane.
The protein forms a voltage-independent potassium channel that is activated by intracellular calcium. This activation leads to membrane hyperpolarization, and the protein is thought to regulate neuronal excitability by contributing to the slow component of synaptic afterhyperpolarization.
KCNN3 is also known as KCa2.3, SK3, SKCA3, ZLS3, hSK3.
