Probable retinal pigment epithelium (RPE)-specific proton-coupled L-lactate transporter (By similarity). May facilitate transport of lactate and H(+) out of the retina and could therefore play an essential role in maintenance of metabolic and ionic homeostasis of the outer retina (PubMed:18524945). (S)-lactate(in) + H(+)(in) = (S)-lactate(out) + H(+)(out) Basolateral sorting signals (BLSS) in C-terminal cytoplasmic tail ensure its basolateral expression (By similarity). Colocalizes with BSG in basolateral cell membrane of the retinal pigment epithelium (PubMed:18524945). Expressed exclusively in retinal pigment epithelium and choroid plexus epithelium. The two basolateral sorting signals (BLSS) in C-terminal cytoplasmic tails direct SLC16A8 to the basolateral membrane. Deficient mice exhibit significant differences in lactate concentration and pH in the retina and display reduced visual function. Belongs to the major facilitator superfamily. Monocarboxylate porter (TC 2.A.1.13) family.