The protein encoded by this gene is a G protein-coupled receptor for sphingosylphosphorylcholine. The encoded protein is a proton-sensing receptor, inactive at pH 7.8 but active at pH 6.8. Mutations in this gene are a cause of amelogenesis imperfecta. [provided by RefSeq, Feb 2017] see less The protein encoded by this gene is a G protein-coupled receptor for sphingosylphosphorylcholine. The encoded protein is a proton-sensing receptor, inactive at pH 7.8 but active at pH 6.8. Mutations in this gene are a cause of amelogenesis imperfecta. [provided by RefSeq, Feb 2017]