Beta-2-microglobulin (B2M)

Part of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.

Exogenously applied M.tuberculosis EsxA or EsxA-EsxB (or EsxA expressed in host) binds B2M and reduces its export to the cell surface (total protein levels do not change), likely resulting in defects in class I antigen presentation (PubMed:25356553).