Monkey IgG, like other mammalian immunoglobulins G （IgG）, is a Y-shaped glycoprotein composed of two identical heavy chains （γ-chains） and two identical light chains （κ or λ）. Each chain contains constant （C） and variable （V） regions. The variable regions form the antigen-binding fragment （Fab）, responsible for recognizing specific antigens, while the constant region （Fc） mediates immune effector functions such as complement activation and binding to Fc receptors on immune cells. Monkey IgG shares structural similarities with human IgG, particularly in conserved domains like the Fc region, which is critical for cross-species applications.