Glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein that interacts via its N-terminal immunoglobulin domain with cell surface receptors including 2B4/CD244 or CD2 to regulate immune cell function and activation (PubMed:27249817, PubMed:12007789). Participates in T-cell signaling transduction by associating with CD2 and efficiently bringing the Src family protein kinase LCK and LAT to the TCR/CD3 complex (PubMed:19494291). In turn, promotes LCK phosphorylation and subsequent activation (PubMed:12007789). Induces the phosphorylation of the cytoplasmic immunoreceptortyrosine switch motifs (ITSMs) of CD244 initiating a series of signaling events that leads to the generation of the immunological synapse and the directed release of cytolytic granules containing perforin and granzymes by T-lymphocytes and NK-cells (PubMed:9841922, PubMed:27249817). Interacts with CD2. Interacts with CD244 (PubMed:9841922, PubMed:27249817). Interacts with LCK (PubMed:12007789). Widely expressed on all hematopoietic cells. By IFN-alpha/beta and IFN-gamma both at the level of CD48 mRNA and cell surface expression.