Phosphatidylserine receptor that plays different role in immune response including phagocytosis of apoptotic cells and T-cell regulation (PubMed:18082433, PubMed:32640697). Involved in efferocytosis, the process by which apoptotic cells are removed by phagocytic cells by promoting the engulfment of apoptotic cells or exogenous particles (PubMed:18082433, PubMed:32703939, PubMed:34067457). Mechanistically, acts by securing apoptotic cells to phagocytes through direct binding to phosphatidylserine present on apoptotic cells, while other engulfment receptors such as MERTK efficiently recognize apoptotic cells and mediate their ingestion (PubMed:32640697). Controls T-cell activation in a bimodal fashion, decreasing the activation of naive T-cells by inducing cell cycle arrest, while increasing proliferation of activated T-cells by activating AKT1 and ERK1/2 phosphorylations and subsequent signaling pathways (By similarity). Also promotes autophagy process by suppressing NLRP3 inflammasome activity via activation of LKB1/PRKAA1 pathway in a phosphatidylserine-dependent mechanism (By similarity). {ECO:0000250|UniProtKB:Q6U7R4, ECO:0000269|PubMed:18082433, ECO:0000269|PubMed:32640697, ECO:0000269|PubMed:32703939, ECO:0000269|PubMed:34067457}. (Microbial infection) Plays a positive role in exosome- mediated trafficking of HIV-1 virus and its entry into immune cells. . This is the function of TIMD4 (T cell immunoglobulin and mucin domain containing 4, Ensembl gene identifier ENSG00000145850).