immunoglobulinsuperfamilien

Immunoglobulin superfamilie (IgSF), or immunoglobulin superfamily, refers to a large and diverse group of proteins that share one or more immunoglobulin-like domains in their extracellular region. These domains are typically about 70–110 amino acids long and adopt a beta-sandwich fold. Proteins in the IgSF can be single-pass transmembrane, multi-pass, secreted, or GPI-anchored, and they often function as receptors, ligands, or cell adhesion molecules.

Ig-like domains in the IgSF mediate protein–protein interactions that underlie cell–cell recognition, adhesion, and signaling. The superfamily encompasses a wide range of proteins with distinct biological roles, from immune recognition to neural development. Although antibodies and B-cell receptors themselves contain immunoglobulin-like regions, the IgSF extends far beyond antibodies to include many receptors, co-receptors, and adhesion molecules.

Representative members include immune system components such as T-cell receptor chains, CD4 and CD8 co-receptors, MHC class I and II molecules, and Fc receptors, as well as cell adhesion molecules like ICAMs, NCAM, L1CAM, and CD2. The IgSF also covers neural guidance and development proteins, such as DSCAM and DCC, illustrating its broad evolutionary reach.

Functions of IgSF proteins are diverse but frequently converge on modulating cell contact and signaling. They participate in antigen presentation, T-cell activation, synapse formation, neurite outgrowth, and tissue organization. Evolutionarily, the IgSF is highly conserved across metazoans and has expanded considerably in vertebrates, providing a modular framework for complex intercellular communication. Clinically, IgSF members are targets for therapies in cancer, autoimmune diseases, and infectious conditions, reflecting their central role in cell communication.