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

Overall, our results suggest that proper targeting of Kre2p in the yeast medial-Golgi may involve two different mechanisms. The saturability of the Kre2p retention system implies a receptor-based retention mechanism that could involve protein-protein interactions over a tail/TMD/ partial stem region. In addition, a second mechanism that may involve oligomerization would operate in some way through the Kre2p luminal domain. In conclusion, our observations on Kre2p targeting may point to differences in Golgi localization mechanisms between yeast and animal glycosyltransferases or could indicate that multiple retention or retrieval mechanisms are used to varying extents in both systems.