Plays a role in cell-cell interaction, cell migration, and angiogenesis. Through interaction with HHLA2, costimulates T-cells in the context of TCR-mediated activation. Enhances T-cell proliferation and cytokine production via an AKT-dependent signaling cascade. . This is the function of Ensembl gene identifier ENSG00000167664 (TMIGD2, transmembrane and immunoglobulin domain containing 2).