Structure and function of human and mouse Fc gamma RII

Receptors for the Fc portion of IgG play an important role in translating the hormonal immune response into activation of various effector cells. Some of the many processes mediated via Fc gamma Rs include endocytosis, phagocytosis, ADCC, superoxide generation, and secretion of lysosomal enzymes and cytokines. There are three different classes of Fc gamma R in humans and mice. These receptors are found on a wide variety of cells including platelets, neutrophils, eosinophils, monocytes, macrophages, large granular lymphocytes, and B lymphocytes. The cDNAs for the human Fc gamma Rs have been cloned and their structures elucidated by sequencing. Recent studies have demonstrated that the cytoplasmic domains of these receptors are crucial for signal transduction. Moreover, there is evidence that different processes triggered by the same receptor seem to require different regions of the cytoplasmic domain. This review will discuss these recent studies correlating Fc gamma R structure and function.