Cisternal Maturation of the Golgi Apparatus in Budding Yeast.

The Golgi apparatus in the budding yeast Saccharomyces cerevisiae, unlike those in mammalian and plant cells, does not form stacks but exists as multiple separate cisternae scattered throughout the cytoplasm. This unique morphological feature has allowed us to observe the spatiotemporal dynamics of individual Golgi cisternae by live cell imaging. Nearly two decades ago, we developed super-resolution confocal live imaging microscopy (SCLIM) and visualized that the yeast Golgi truly matures, i.e., a single cisterna gradually changes its nature from cis to trans cisternae over time. Since then to date, many researchers have observed a wide variety of proteins residing in and around the Golgi, as well as cargoes, in live yeast cells, unveiling the detailed step-by-step processes of Golgi cisternal maturation. Notably, our recent studies identified the ER-Golgi intermediate compartment (ERGIC) in budding yeast, which matures into the cis Golgi. After cis-to-trans maturation, the trans Golgi further matures into the trans-Golgi network (TGN), which can be divided into at least two sub-stages, the early and late TGN. Altogether, accumulating evidence revealed that the Golgi apparatus is not a static, but rather a highly dynamic organelle that appears transiently with a short lifetime along with cargo traffic.