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The human serum immunoglobulins IgG and IgA1 are produced in bone marrow and both interact with specific cellular receptors that mediate biological events. In contrast to IgA1, the glycosylation of IgG has been well characterized, and its interaction with various Fc receptors (Fc Rs) has been well studied. In this paper, we have analyzed the glycosylation(More)
Immunoglobulins couple the recognition of invading pathogens with the triggering of potent effector mechanisms for pathogen elimination. Different immunoglobulin classes trigger different effector mechanisms through interaction of immunoglobulin Fc regions with specific Fc receptors (FcRs) on immune cells. Here, we review the structural information that is(More)
Human immunoglobulin A (IgA) is an abundant antibody that mediates immune protection at mucosal surfaces as well as in plasma. The IgA1 isotype contains two four-domain Fab fragments and a four-domain Fc fragment analogous to that in immunoglobulin G (IgG), linked by a glycosylated hinge region made up of 23 amino acid residues from each of the heavy(More)
Immunoglobulin A (IgA) has a critical role in immune defense particularly at the mucosal surfaces, and is equipped to do so by the unique structural attributes of its heavy chain and by its ability to polymerize. Here, we provide an overview of human IgA structure, describing the distinguishing features of the IgA1 and IgA2 subclasses and mapping the sites(More)
Certain pathogenic bacteria express surface proteins that bind to the Fc part of human IgA or IgG. These bacterial proteins are important as immunochemical tools and model systems, but their biological function is still unclear. Here, we describe studies of three streptococcal proteins that bind IgA: the Sir22 and Arp4 proteins of Streptococcus pyogenes and(More)
The vast surfaces of the gastrointestinal, respiratory, and genitourinary tracts represent major sites of potential attack by invading micro-organisms. Immunoglobulin A (IgA), as the principal antibody class in the secretions that bathe these mucosal surfaces, acts as an important first line of defence. IgA, also an important serum immunoglobulin, mediates(More)
Due to their vast surface area, the mucosal surfaces of the body represent a major site of potential attack by invading pathogens. The secretions that bathe mucosal surfaces contain significant levels of immunoglobulins (Igs), which play key roles in immune defense of these surfaces. IgA is the predominant antibody class in many external secretions and has(More)
Receptors for immunoglobulins (Fc receptors) play a central role during an immune response, as they mediate the specific recognition of antigens of almost infinite diversity by leucocytes, thereby linking the humoral and cellular components of immunity. Indeed, engagement of Fc receptors by immunoglobulins initiates a range of immunoregulatory processes(More)