Cell adhesion molecule that mediates cell-cell contacts and regulates T-cell responses via its interaction with ALCAM/CD166 (  , ). Contributes to signaling cascades triggered by activation of the TCR/CD3 complex . Functions as a costimulatory molecule; promotes T-cell activation and proliferation ( ). Contributes to the formation and maturation of the immunological synapse (, ). Functions as a calcium-dependent pattern receptor that binds and aggregates both Gram-positive and Gram-negative bacteria. Binds both lipopolysaccharide (LPS) from Gram-negative bacteria and lipoteichoic acid from Gram-positive bacteria . LPS binding leads to the activation of signaling cascades and down-stream MAP kinases . Mediates activation of the inflammatory response and the secretion of pro-inflammatory cytokines in response to LPS .
Subcellular locations: Cell membrane
Detected at the immunological synapse, i.e, at the contact zone between antigen-presenting dendritic cells and T-cells (, ). Colocalizes with the TCR/CD3 complex at the immunological synapse .
Subcellular locations: Secreted
The origins of the secreted form are not clear, but it might be created by proteolytic shedding of the ectodomain.
Detected on thymocytes . Detected on peripheral blood T-cells (, ). Detected on natural killer (NK) cells . Soluble CD6 is detected in blood serum (at protein level) . Detected in spleen, thymus, appendix, lymph node and peripheral blood leukocytes . Expressed by thymocytes, mature T-cells, a subset of B-cells known as B-1 cells, and by some cells in the brain.