Together with MHC-II, associates with lipid-enriched microdomains called tetraspanin-enriched microdomains (TEMs). Rapidly translocates into immunological synapse (IS) at cell-cell contacts between antigen-presenting cells (APCs) and T-cells. Colocalized with tetraspanins CD37, CD53, and CD81 at the uropod. Present at regions of cell-cell contacts but also at the leading edge of migrating cells.