Selective anchoring in the specific plasma membrane domain: a role in epithelial cell polarity

Recent work has shown that signals for the retention of proteins in the ER may be localized in either luminal (47) or cytoplasmic (53) domains (see reference 62 for a review). Plasma membrane proteins lacking these signals would be carried by bulk flow to the Golgi apparatus and then to the cell surface. With the exception of Band III, there is no evidence for the localization of retention signals in plasma membrane proteins. It has recently been reported that major histocompatibility antigens or epidermal growth factor with truncated tails do not show increased lateral diffusion (23, 37) . A similar result has been reported for vesicular stomatitis virus (VSV) G glycoprotein (66) , suggesting the possibility that protein-protein interactions at the ectoplasmic domain may result in restrictions to lateral mobility of membrane proteins.