Fragment crystallizable region of antibody (Fc region)

The **Fc region of an antibody** is the constant tail portion of the molecule composed of paired constant domains from the heavy chains (CH2, CH3, and sometimes CH4)[1][3][6]. It mediates immune responses by binding to cellular Fc receptors (on macrophages, NK cells, and other leukocytes) and complement proteins, enabling effector functions such as antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC)[3][5][8]. The Fc region is commonly engineered in therapeutic antibodies to modify serum half-life, effector function strength, and specificity for different Fc receptors or immune system pathways[8]. Some clinical biomarkers, such as certain Fc gamma receptor polymorphisms, can predict patient response to specific therapeutic antibodies with engineered Fc regions[8]. Although critical for therapeutic efficacy, the Fc region itself is not considered a classic drug target or receptor, but rather a protein domain modified to optimize antibody therapies. For highly structured information, use the full scientific name "Fragment crystallizable region of antibody" and abbreviation "Fc region." Note that this entry is a *structure*, not a canonical molecular target.

Other names

Fc fragmentFragment crystallizable regionImmunoglobulin constant region

Mediates effector functions via Fc receptor binding (e.g., antibody-dependent cellular cytotoxicity [ADCC], antibody-dependent cell-mediated phagocytosis [ADCP], complement-dependent cytotoxicity [CDC]) Engages complement pathway for cell lysis