Based on limited published evidence, SLC36A3 encodes a proton-coupled amino acid transporter belonging to the SLC36 family. GO annotations indicate it possesses amino acid:proton symporter activity with substrate specificity for glycine, L-alanine, and L-proline. However, SLC36A3 remains functionally orphaned—its physiological role is unknown 1. Expression is restricted to testis tissue 2, suggesting a specialized reproductive function distinct from other SLC36 family members (SLC36A1-A2, which mediate intestinal/renal amino acid absorption). The molecular mechanisms and biological significance of SLC36A3-mediated transport require further investigation.