Enables antigen binding activity and protein domain specific binding activity. Involved in several processes, including cellular response to cytokine stimulus; response to cobalamin; and response to interferon-gamma. Located in several cellular components, including cell surface; neuronal cell body; and varicosity. Used to study several diseases, including Ehrlich tumor carcinoma; artery disease (multiple); colitis; membranous glomerulonephritis; and obesity. Biomarker of asthma; atherosclerosis; and perinatal necrotizing enterocolitis. Human ortholog(s) of this gene implicated in several diseases, including Kawasaki disease; autoimmune disease (multiple); end stage renal disease; hyperimmunoglobulin syndrome (multiple); and non-Hodgkin lymphoma (multiple). Orthologous to human CD40 (CD40 molecule). [provided by Alliance of Genome Resources, Apr 2022]