Alpha-kinase domain of channel kinase 2, also called transient receptor potential cation channel subfamily M member 6
Channel kinase 2 (ChaK2), also called transient receptor potential cation channel subfamily M member 6 (TRMP6) or melastatin-related TRP cation channel 6, is a fusion protein containing a transmembrane ion pore or channel and a C-terminal alpha-kinase domain, both of which are functional. It is highly expressed in the kidney and instestine. It is a cation-selective channel that preferentially permeates Zn2+, Mg2+, and Ca2+ ions. It is a central regulator of Mg2+ and Ca2+ homeostasis. TRPM6 is considered to be the Mg2+ entry pathway in the distal convoluted tubule of the kidney, where it functions as a gatekeeper for controlling the body's Mg2+ balance. Mutations in the TRPM6 gene cause the autosomal recessive disorder hypomagnesemia with secondary hypocalcemia, which often results in severe muscular and neurologic complications from early infancy that can lead to neurologic damage or cardiac arrest if left untreated. Alpha-kinase is an atypical protein kinase catalytic domain with no detectable similarity to conventional protein serine/threonine kinases. The alpha-kinase family was named after the unique mode of substrate recognition by its initial members, the Dictyostelium heavy chain kinases, which targeted protein sequences that adopt an alpha-helical conformation. More recently, alpha-kinases were found to also target residues in non-helical regions.
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