ABCB9 Gene - ATP Binding Cassette Subfamily B Member 9 | Function, Mutations & Disease

ABCB9 encodes a member of the ATP-binding cassette (ABC) transporter superfamily. The protein, also known as TAP-like (TAPL), is localized to lysosomal and endosomal membranes and functions as a peptide transporter. It is involved in the translocation of peptides from the cytosol into lysosomes, potentially contributing to antigen processing and presentation via MHC class I-like molecules. ABCB9 is expressed in various tissues, with highest levels in testis, brain, and immune cells. Alterations in ABCB9 expression or function have been linked to cancer progression and neurodegenerative conditions.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Antigen processing and presentation (Reactome: R-HSA-1236974)

• ABC transporter family (KEGG: hsa02010)

ABCB9 (TAPL) is a 766-amino acid ABC transporter with two transmembrane domains and two nucleotide-binding domains. It forms a homodimer that translocates peptides from the cytosol into lysosomes in an ATP-dependent manner. The protein is essential for lysosomal peptide loading onto MHC class I-like molecules (e.g., CD1d) and may influence immune responses. Structural studies reveal a conserved ABC transporter fold with a peptide-binding pocket.