KCNJ13: Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. Their voltage dependence is regulated by the concentration of extracellular potassium; as external potassium is raised, the voltage range of the channel opening shifts to more positive voltages. The inward rectification is mainly due to the blockage of outward current by internal magnesium. KCNJ13 has a very low single channel conductance, low sensitivity to block by external barium and cesium, and no dependence of its inward rectification properties on the internal blocking particle magnesium. Defects in KCNJ13 are the cause of snowflake vitreoretinal degeneration (SVD). SVD is a developmental and progressive hereditary eye disorder that affects multiple tissues within the eye. Diagnostic features of SVD include fibrillar degeneration of the vitreous humor, early-onset cataract, minute crystalline deposits in the neurosensory retina, and retinal detachment. Defects in KCNJ13 are the cause of Leber congenital amaurosis type 16 (LCA16). LCA16 is a severe dystrophy of the retina, typically becoming evident in the first years of life. Visual function is usually poor and often accompanied by nystagmus, sluggish or near-absent pupillary responses, photophobia, high hyperopia and keratoconus. Belongs to the inward rectifier-type potassium channel (TC 1.A.2.1) family. KCNJ13 subfamily. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: Membrane protein, integral; Channel, potassium; Membrane protein, multi-pass
Chromosomal Location of Human Ortholog: 2q37
Cellular Component: integral to plasma membrane
Molecular Function: inward rectifier potassium channel activity
Biological Process: potassium ion import
Disease: Leber Congenital Amaurosis 16; Vitreoretinal Degeneration, Snowflake Type
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