Enables T cell receptor binding activity and endogenous lipid antigen binding activity. Involved in NK T cell differentiation and regulation of immature T cell proliferation in thymus. Acts upstream of or within several processes, including antigen processing and presentation, exogenous lipid antigen via MHC class Ib; positive regulation of cytokine production; and positive regulation of leukocyte activation. Located in endosome; external side of plasma membrane; and lysosome. Is expressed in forebrain; intestine; jaw bone; and liver. Human ortholog(s) of this gene implicated in pulmonary tuberculosis. Orthologous to human CD1D (CD1d molecule). [provided by Alliance of Genome Resources, Apr 2022]