The process of protein biogenesis culminates in its correct targeting to specific subcellular locations where it serves a function. Contemporary molecular and cell biology investigations often involve the exogenous expression of epitope- or fluorescent protein-tagged recombinant molecules as well as subsequent analysis of protein-protein interactions "in vitro" and "in vivo." Fundamental knowledge of targeting signals that direct a polypeptide to various organelles or membrane domains is essential for the proper design of such recombinant molecules. A fundamental concept of membrane compartmentalization is also often useful for the interpretation of the preliminary results of interaction screens. Knowledge in targeting signals and post-translational dynamics of proteins should therefore be given sufficient emphasis in an undergraduate biochemistry or molecular biology curriculum. Such knowledge is essential, particularly for undergraduates or fresh graduates embarking on research projects in a cell and molecular biology laboratory.