MACROPINOCYTOSIS

Macropinocytosis is a form of endocytosis that accompanies cell surfac e ruffling. It is district in many ways from the better characterized micropinocytosis, which includes clathrin-coated vesicle endocytosis a nn small uncoated vesicles. Because macropinosomes are relatively larg e, they provide an efficient route for non-selective endocytosis of so lute macromolecules. This route may facilitate MHC-class-II-restricted antigen presentation by dendritic cells. Because the ruffling that le ads to macropinocytosis is regulated, it has been exploited by some pa thogenic bacteria as a novel route for entry into cells.