This gene is predominantly expressed in the kidney and colon, and encodes a protein containing an ion channel domain and a protein kinase domain. It is crucial for magnesium homeostasis, and plays an essential role in epithelial magnesium transport and in the active magnesium absorption in the gut and kidney. Mutations in this gene are associated with hypomagnesemia with secondary hypocalcemia. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene. [From RefSeq]