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

In the case of KD-K, only partial interaction would occur with the putative receptor and the observed Golgi retention may now reveal an additional mechanism involving a segment of the Kre2p luminal region possibly by oligomerization/kin recognition that has been implicated in the retention of certain mammalian Golgi'membrane proteins. It has been proposed that protein oligomers are assembled through their TMD and/or luminal domains in a particular Golgi cisternae and because of their highorder structure are consequently excluded from entering forward-moving secretory vesicles (Weisz et al., 1993; Gleeson et al., 1994; Low and Hong, 1994; Nilsson et al., 1994; Schweizer et al., 1994; Yamaguchi and Fukuda, 1995) . Applying such a model to a functionally active Kre2 protein involves self-association or formation of heterooligomers between Kre2p and other medial-Golgi protein(s) either through the catalytic domain or possibly with some contiguous stem sequences retained in construct