Lipid tetraspanin-associated transmembrane adapter/mediator that acts as a scaffold for Src-family kinases and other signaling proteins in immune cells . It is involved in major histocompatibility complex class II (MHC-II) signaling transduction in B cells, where it is required in generating the calcium response and enhancing ERK activity upon MHC-II stimulation . In dendritic cells, it is involved in sustaining CLEC7A/DECTIN1 signaling after CLEC7A activation by fungal beta-glucans (By similarity). It also acts as an agonist-inducible signaling adapter for TLR1, TLR2, TLR3, TLR4, and TLR7 by selectively enabling the expression of pro-inflammatory cytokines IL6 and IL12B in macrophages and acting as a scaffold for phosphorylation of Toll-like receptors by Src-family kinases (By similarity).
Subcellular locations: Cell membrane, Cell membrane, Cytoplasmic vesicle, Phagosome, Cell projection, Ruffle, Cell projection, Filopodium
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 . Localizes to phagosomes in dendritic cells after exposure to particulate beta-glucan (By similarity).
Expressed in antigen-presenting cells, like peripheral blood leukocytes and monocyte-derived dendritic cells (MDDC) (at protein level) . Highly expressed in lymph nodes and spleen. Expressed in antigen-presenting cells . Faintly expressed in the majority of nonimmune system tissues .