Immunoglobulin G1 antibody Fc region (IgG1 Fc)

The Immunoglobulin G1 antibody Fc region (IgG1 Fc) is the constant tail portion of the IgG1 antibody. It is formed by the C-terminal domains of the heavy chains (CH2 and CH3) and is linked by disulfide bonds and non-covalent interactions. The Fc region is distinct from the Fab (antigen-binding) arms and is highly conserved within a species. Its central role is to mediate various immune effector functions by engaging specific cell surface Fc gamma receptors (FcγRs) and complement proteins, leading to activities such as ADCC, CDC, phagocytosis, and immune modulation. The IgG1 Fc also binds to the neonatal Fc receptor (FcRn), governing antibody half-life and recycling. Therapeutic monoclonal antibodies are commonly formatted as human IgG1 because its Fc region robustly recruits immune effector mechanisms and is well characterized. Engineering of the IgG1 Fc region can tune effector functions, stability, and pharmacokinetics, but may also introduce safety or immunogenicity risks.

Other names

IgG1 Fc fragmentIgG1 crystallizable fragmentIgG1 fragment crystallizable regionFc region of IgG1

Fcγ receptor engagement mediating effector cell activation (e.g., NK cell-mediated ADCC); Complement binding leading to complement-dependent cytotoxicity (CDC); Neonatal Fc receptor (FcRn) binding regulating antibody half-life and transport; Immune complex formation and opsonization