adapten

Adapten is a term that occasionally appears in scientific writings as an alternative form of adaptin, one of the adaptor protein subunits involved in clathrin-mediated vesicular trafficking. In standard nomenclature, the proteins are called adaptins or adaptor proteins, and individual complexes are designated AP-1, AP-2, AP-3, and AP-4.

Adaptins form heterotetrameric complexes that recruit clathrin to membranes and recognize sorting signals on cargo receptors, enabling selective incorporation of cargo into clathrin-coated vesicles. AP-1 operates mainly at the trans-Golgi network and endosomes, while AP-2 functions at the plasma membrane to mediate endocytosis. AP-3 and AP-4 participate in trafficking pathways from the Golgi to lysosome-related organelles and other post-Golgi routes, respectively. Each adaptor complex comprises two large subunits, one medium μ subunit, and one small σ subunit, and they coordinate cargo selection with coat assembly.

Mechanistically, adaptins undergo conformational changes that regulate cargo binding and coat formation. They interact with cargo motifs such as tyrosine-based YXXΦ signals and dileucine-based motifs, linking cargo receptors to the clathrin coat and shaping vesicle formation.

Clinical relevance reflects the essential role of adaptor proteins in cellular logistics. Genetic defects in AP subunits disrupt intracellular trafficking and can contribute to human disease, including disorders affecting pigmentation and neurological development in some cases.

Evolutionarily, adaptins are conserved across a broad range of eukaryotes, reflecting their fundamental role in vesicular transport. The term adapten is largely considered a variant spelling or historical usage of adaptin, rather than a distinct Wikipedia-style entry. See also adaptin, clathrin, vesicular trafficking.