Through interaction with TMIGD2, costimulates T-cells in the context of TCR-mediated activation. Enhances T-cell proliferation and cytokine production via an AKT-dependent signaling cascade. Interacts with TMIGD2. Expressed at high levels in colon, kidney, testis, lung and pancreas, and at lower levels in small intestine, liver and skeletal muscle. In immune cells, highly expressed in B-cells, dendritic cells and macrophages. Not detected in T-cells. Up-regulated in antigen-presenting cells in response to inflammation. Induced in dendritic cells in response to IFNG, poly(I:C) or heat-killed Listeria monocytogenes (at protein level). Truncated C-terminus.