CHRNA9
Description
The CHRNA9 (cholinergic receptor nicotinic alpha 9 subunit) is a protein-coding gene located on chromosome 4.
The CHRNA9 gene encodes the Neuronal acetylcholine receptor subunit alpha-9 (nAChRα9), a protein forming a subunit of certain nicotinic acetylcholine receptors. These α9 subunit-containing receptors are notably blocked by nicotine, but the role of this antagonism in tobacco effects is unclear. This gene belongs to the ligand-gated ionic channel family and the nicotinic acetylcholine receptor gene superfamily, encoding a plasma membrane protein that forms homo- or hetero-oligomeric divalent cation channels. CHRNA9 is involved in cochlea hair cell function, being expressed in both inner and outer hair cells (OHCs) of the adult cochlea, though expression is low in adult inner hair cells. Activation of the alpha9/10 nAChR is via olivocochlear activity, originating from the superior olive region of the brainstem. This protein is also found in keratinocytes, the pituitary gland, B-cells, and T-cells. The conotoxin RgIA selectively blocks α9α10 nicotinic acetylcholine receptors, demonstrating analgesic effects in an animal model of nerve injury pain.
Ionotropic receptor involved in the modulation of auditory stimuli. Upon agonist binding, it undergoes a conformational change opening an ion-conducting channel across the plasma membrane. The channel is permeable to divalent cations such as calcium, whose influx can activate a potassium current, leading to hyperpolarization of the cell membrane. This process may reduce basilar membrane motion in the ear, affecting auditory nerve fiber activity and reducing dynamic hearing range, potentially protecting against acoustic trauma. Additionally, CHRNA9 may also regulate keratinocyte adhesion.
CHRNA9 is also known as HSA243342, NACHRA9.
