PIN-G reporter for imaging and defining trafficking signals in membrane proteins

The identification of motifs that control the intracellular trafficking of proteins is a fundamental objective of cell biology. Once identified, such regions should, in principle, be both necessary and sufficient to direct any randomly distributed protein, acting as a reporter, to the subcellular compartment in question. However, most reporter proteins have limited versatility owing to their endogenous expression and limited modes of detection--especially in live cells. To surmount such limitations, we engineered a plasmid--pIN-G--encoding an entirely artificial, type I transmembrane reporter protein (PIN-G), containing HA, cMyc and GFP epitope, and fluorescence tags. Although originally designed for trafficking studies, pIN technology is a powerful tool applicable to almost every area of biology. Here we describe the methodologies used routinely in analyzing pIN constructs and some of their derivatives.