Immunoglobulin Fc Receptors: Linking Humoral Immunity with Immune Cell Function

摘要

An antibody molecule is composed of two heavy chains and two light chains joined together by a series of disulfide bonds. The antibody molecule is quite flexible and can change its shape due to the flexibility generated around these disulfide bonds. Together, the heavy and light chains form the classic "Y" shape of an antibody molecule. Functionally, the antibody molecule is composed of an antigen-binding region, also known as the variable region, which has two identical antigen-binding sites (each arm of the "Y"). The other end of the antibody molecule contains the Fc region (the biochemical designation of the crystallizable fragment of the molecule). Unlike the antigen-binding regions, each of which are unique to the plasma cell producing them, the Fc region of the antibody molecule is relatively constant. The five classes of immunoglobulins, IgA, IgD, IgE, IgG, and IgM are defined by their constant region. Specialized receptors, known as Fc receptors (FcRs), interact with the Fc portion of antibody molecules to coordinate the immune response.