Plasmolipin is an 18 kDa membrane-bound proteolipid that belongs to the tetraspan (4TM) family, a rapidly growing group of myelin-associated proteins. Many of these proteins could be linked to human hereditary demyelinating neuropathies. Studies indicate that plasmolipin is a component of the cytoskeletal structure and has been localized to the apical surface of tubular epithelial cells. It has been shown that, upon addition to lipid bilayers, plasmolipin induces formation of ion channels that are both voltage-dependent and potassium-specific. Plasmolipin was originally isolated from kidney tissue. Subsequently, it has been shown to be widely expressed, not only being present in kidney, but also in the nervous system, thymus, testis, lung, and thyroid gland.