Enables several functions, including antigen binding activity; identical protein binding activity; and immunoglobulin receptor binding activity. Acts upstream of or within several processes, including early endosome to late endosome transport; immunoglobulin mediated immune response; and positive regulation of B cell proliferation. Located in external side of plasma membrane; extracellular space; and perinuclear region of cytoplasm. Part of B cell receptor complex and immunoglobulin complex, circulating. Is expressed in several structures, including brain; hemolymphoid system; and liver. Used to study non-Hodgkin lymphoma and type 1 diabetes mellitus. Human ortholog(s) of this gene implicated in agammaglobulinemia. Orthologous to human IGHM (immunoglobulin heavy constant mu).
