Tetraspanin 2 (TSPAN2) is a member of the Tetraspanin family of proteins, that comprises 33 members in humans. The family is characterized by the presence of four transmembrane domains, which give rise to the name "tetraspanin”, as well as the presence two extracellular loops (EC1 and EC2), a small cytoplasmic loop, and short N- and C-terminal tails ^1,2.

Tetraspanins are able to interact with each other and also with numerous partner proteins such as integrins, growth factor receptors and ion channels, to create a dynamic network of interactions known as the tetraspanin-enriched microdomains (TEMs). Consequently, tetraspanins are regarded as molecular organizers and by forming complexes with these proteins, tetraspanins can modulate signal transduction pathways and cellular responses ^2,3,4.

Although TSPAN2 shares a relatively high homology with well-studied tetraspanins like CD9 (TSPAN29) or CD81 (TSPAN28), it has been less well-characterised up until now ³.

Nevertheless, TSPAN2, like the related CD9 and CD81 proteins, has been described in relation to exosome formation, specifically regarding neuroinflammation and microglia activation ⁵, as well as oligodendrocyte differentiation into myelin-forming glia and in the progression of tumor metastasis by modulating cancer cell motility and invasion ^3,5.