Transport of small hydrophilic substances across cell membranes is mediated by substrate-specific transporter proteins which have been classified into several families of related genes. The protein encoded by this gene belongs to the sodium:neurotransmitter symporter (SNF) family and functions as a proline transporter expressed in kidney and small intestine. Mutations in this gene are associated with Hyperglycinuria and Iminoglycinuria. [provided by RefSeq, Jul 2020]