Evaluation of unconventional protein secretion in Saccharomyces cerevisiae

Recent development of large-scale analyses such as the secretome analysis has enabled the discovery of a vast number of intracellular proteins that are secreted outside the cell. Often, these proteins do not contain any known signal sequence required for conventional protein secretion. In order to avoid misidentification of such "leaked" proteins as "secreted" proteins, reconstructing the process of protein secretion is essential. Here, we describe methods for the detection of reconstructed unconventional protein secretion and determination of regulatory proteins of secretion in Saccharomyces cerevisiae. We show that conjugating target proteins with a tag-sequence and utilizing various reagents and tools can facilitate quantitative detection of the secretion of target proteins. We expect that these methods will reveal novel unconventional secretion pathways of proteins.