Figure 2.

Schematic drawing showing cellular functions of tetraspanins. Tetraspanins associate with integrins, Ig superfamily proteins, and other transmembrane proteins. Additionally, tetraspanins are in molecular complex with cytoplasmic proteins, such as syntenin-1 (s) and signalling molecules. Tetraspanin containing complexes are designated as ‘tetraspanin web’ or ‘tetraspanin enriched microdmians’ (TEM). In addition to serving as organizers at the plasma membrane, tetraspanins are also enriched in the intracellular vesicles. Trafficking of tetraspanins between various cellular compartments tightly regulates exocytosis and trafficking of their associated partners. Tetraspanins in conjunction with other membrane proteins regulate cell–extracellular matrix adhesion, cell–cell interactions, cell migration, and modulate intracellular signaling events. Tetraspanins regulate phenomena such as vascular injury response, angiogenesis, heterotypic cell contacts, and tumour invasion and metastasis.