Polarized sorting of GPI-linked proteins in epithelia and membrane microdomains.

Taken together, our results with endogenous and transfected GPI-anchored proteins (summarized in Table 6) suggest that covalent attachment to GPI functions as an apical transport signal in polarized epithelial cells. This is the first example of a well-defined targeting signal for the post-Golgi sorting of plasma membrane proteins in polarized epithelia; the only other known post-Golgi targeting signal is mannose-6-phosphate, which functions in the recognition of lysosomal hydrolases and directs them to lysosomes.