Enables protein heterodimerization activity. Involved in amino acid transport and gene expression. Located in apical plasma membrane and brush border membrane. Is expressed in several structures, including brain; genitourinary system; integumental system; intestine; and respiratory system. Used to study cystinuria. Human ortholog(s) of this gene implicated in cystinuria. Orthologous to human SLC3A1 (solute carrier family 3 member 1). [provided by Alliance of Genome Resources, Apr 2022]