Nestled in the membranes of human cells exists a type of difficult to find protein that we call tetraspanin. Tetraspanins are a family of membrane proteins found in all multicellular eukaryotes (cells that are enclosed by a plasma membrane and contain a nucleus). They are a large superfamily of cell surface membrane proteins characterised by their four transmembrane domains. Tetraspanins' vesicle function plays a role in a variety of processes such as cellular adhesion and motility (the ability of an organism to move independently, using metabolic energy). It is thought they may be involved in the organzisation of cell surface membrane microdomains that regulate the activation of leucocytes (colourless (white) cells that circulate in blood and bodily fluids, that are involved in impeding disease and foreign substances).
So far tetraspanins by themselves have not demonstrated any innate signalling pathway stimulations. More, they act as molecular organisers of cells' plasma membrane and assist the actions of their associate molecules such as integrins (any of a category of transmembrane proteins that are involved in the fixing of cells to each other and to their underlying layer).
The tetraspanin molecule itself adopts an uncommon shape in which the four parts that cross the membrane come in two pairs, producing V-shape. A large chamber exists within the shape in which cholesterol can settle. It is believed that the cholesterol occupying this space may have the capability to control whether the 'cover' that extends between these two arms of the V remains open or closed.
Tetraspanins are known to undertake a range of tasks. However, recent studies have linked them to some diseases. This discovery fostered a desire to gain greater detail of the tetraspanin vesicle function and of their composition as a whole. Scientists at Harvard University recently embarked upon a project to replicate the full molecular structure of the tetraspanin, through a method of capturing and crystalising the structure. The study was undertaken with the hope of enabling future researchers and scientists, equipped with a better understanding of their mechanisms and purposes, to promote the prospects of preventing disease in through further future research.