Enables L-proline transmembrane transporter activity. Involved in proline import across plasma membrane. Acts upstream of or within amino-acid betaine transport and proline transmembrane transport. Located in apical plasma membrane. Is expressed in early conceptus; metanephros; and secondary oocyte. Human ortholog(s) of this gene implicated in iminoglycinuria. Orthologous to human SLC6A20 (solute carrier family 6 member 20). [provided by Alliance of Genome Resources, Apr 2022]