Also known as Immunoglobulin Heavy Constant Gamma 1 (G1m Marker), Human IgG1 encodes the Ig gamma-1 chain C region protein. Circulating in the extracellular region, Human IgG1 can also be found in the membrane and plays a role in membrane fraction. More specifically, the main molecular function of Human IgG1 is antigen and protein binding. Biological processes for this protein include phagocytosis, immune response, complement activation, innate immune response and complement activation in the classical pathway. There are 120 known interacting proteins and the most common diseases associated with IgG1 include multiple myeloma and leukemia.