The IgG1 protein is the constant region of the immunoglobulin heavy chain and serves as a receptor during the recognition phase of humoral immunity. It triggers clonal expansion and differentiation of B lymphocytes into immunoglobulin-secreting plasma cells. IgG1 Protein, Human (CHO, C103S) is the recombinant human-derived IgG1 protein, expressed by CHO , with tag free.