Localization and targeting of the Saccharomyces cerevisiae Kre2p/Mnt1p alpha 1,2-mannosyltransferase to a medial-Golgi compartment

Here we report further characterization of the KRE2/ MNTl-encoded mannosyltransferase. We demonstrate that Kre2p/Mntlp possesses a type II orientation, is progressively N-glycosylated in an MNNl-dependent fashion, and is localized in a Golgi subcompartment that overlaps with the Mnnlp medial-Golgi compartment. In addition, we show that the short NH2-terminal cytoplasmic tail domain of Kre2p/Mntlp is required for correct Golgi localization, whereas the membrane-spanning and stem domains are dispensable. However, localization of a reporter protein to the yeast Golgi requires a region of Kre2p/Mntlp encompassing the cytoplasmic tail, the transmembrane domain (TMD), and a segment of the luminal stem domain.