Routes to and from the plasma membrane: bulkflow versus signal mediated endocytosis

摘要

Transport of proteins via the secretory pathway is controlled by a combination of signal dependent cargo selectionas well as unspecific bulkflow of membranes and aqueous lumen. Using the plant vacuolar sorting receptor as modelfor membrane spanning proteins, we have distinguished bulkflow from signal mediated protein targeting inbiosynthetic and endocytic transport routes and investigated the influence of transmembrane domain length. Morespecifically, long transmembrane domains seem to prevent ER retention, either by stimulating export or preventingrecycling from post ER compartments. Long transmembrane domains also seem to prevent endocytic bulkflow fromthe plasma membrane, but the presence of specific endocytosis signals overrules this in a dominant manner.