ATP-dependent low-affinity peptide transporter which translocates a broad spectrum of peptides from the cytosol to the lysosomal lumen for degradation (   , ). Displays a broad peptide length specificity from 6-mer up to at least 59-mer peptides with an optimum of 23-mers (, ). Binds and transports smaller and larger peptides with the same affinity . Favors positively charged, aromatic or hydrophobic residues in the N- and C-terminal positions whereas negatively charged residues as well as asparagine and methionine are not favored ( ).
Subcellular locations: Lysosome membrane
May be located in membrane rafts. Takes an intracellular route from the endoplasmic reticulum (ER), via Golgi and early endosomes to late endosomal and lysosomal compartments .
Highly expressed in testis, and at moderate levels in brain, spinal cord, and thyroid. Not expressed in monocytes but strongly expressed during differentiation of monocytes to dendritic cells and macrophages.