Intracellular traffic of newly synthesized proteins. Current understanding and future prospects.

Our survival depends on the specialized functions of our tis- sues and organs. These functions are carried out by specific proteins, i.e., enzymes, receptors, and channels, which reside in specific locations within the cell, separated by membranes. Indeed, most of the activities characteristic of a tissue can be traced back to individual gene products expressed in a particular membrane or membrane-delimited compartment. Mislo- calization of such proteins is functionally equivalent to lack of expression, or worse.