Cellular component

An IgM immunoglobulin complex that is present in the plasma membrane of B cells and is composed of two identical immunoglobulin heavy chains of the IgM isotype and two identical immunoglobulin light chains and a signaling subunit, a heterodimer of the Ig-alpha and Ig-beta proteins.

Note that an IgM immunoglobulin complex has the function of antigen binding if a suitable antigen is available.