Adhesion-GPCRs: emerging roles for novel receptors

The G protein-coupled receptor (GPCR) family comprises the largest class of cell surface receptors found in metazoan proteomes. Within the novel GPCR subfamily of adhesion-GPCRs, ∼150 distinct orthologues, from invertebrates to mammals, have been identified to date. All members of this family contain a large extracellular region, often containing common protein modules, coupled to a seven-transmembrane domain via a stalk region that seems to be crucial for functionality. Owing to their unique structure, restricted expression profile and involvement in several human diseases, adhesion-GPCRs have long been proposed to have vital dual roles in cellular adhesion and signalling. More recent studies have provided structural, evolutionary, developmental and immunological insights in relation to the adhesion-GPCR family. The G protein-coupled receptor (GPCR) family comprises the largest class of cell surface receptors found in metazoan proteomes. Within the novel GPCR subfamily of adhesion-GPCRs, ∼150 distinct orthologues, from invertebrates to mammals, have been identified to date. All members of this family contain a large extracellular region, often containing common protein modules, coupled to a seven-transmembrane domain via a stalk region that seems to be crucial for functionality. Owing to their unique structure, restricted expression profile and involvement in several human diseases, adhesion-GPCRs have long been proposed to have vital dual roles in cellular adhesion and signalling. More recent studies have provided structural, evolutionary, developmental and immunological insights in relation to the adhesion-GPCR family. or programmed cell death, is a form of cell death whereby the cell activates an internal cell-death program. Apoptosis contrasts with necrosis, death caused by external factors (e.g. phagocytosis of apoptotic cells results in non-inflammatory uptake by phagocytes, whereas phagocytosis of necrotic cells results in inflammation). is the failure to respond to an antigen; the immune system is tolerant to self-antigens. The tolerance to self-antigens is a critical feature of the immune system; when tolerance is defective, the immune system can destroy self antigens, as observed in auto-immune disease. The immune system becomes tolerant to self-antigens during lymphocyte development. a large mononuclear phagocyte that is important in the innate immune response and in humoral and cell-mediated immunity. Macrophages are migratory cells derived from bone marrow precursors and are found in most tissues in the body. a subset of leukocytes (white blood cells) possessing multi-lobed nuclei composed of cytoplasmic granules. There are three types of PMNs: neutrophils, eosinophils and basophils. Neutrophils are the most abundant circulating leukocyte in humans and are recruited to inflammatory sites, where they are predominately involved in the engulfment and killing of pathogens.