Figure 8.

Hypothetical model describing the targeting of callose-modifying Pd-associated GPI-anchored proteins (Pd GPI-APs) and non-Pd GPI-APs. After attachment of the GPI anchor (black string) in the ER and its subsequent remodeling (not shown), both groups of GPI-APs enter the secretory pathway. The remodeled GPI-APs partition into specialized membrane microdomains (red) in the Golgi membranes. The Pd-associated GPI-APs are sorted into microdomain-rich clusters, whereas the non-Pd GPI-APs are sorted out from such clusters by means of signals associated with their ectodomains. Vesicles formed from respective regions of the Golgi membranes deliver the GPI-APs to the PM, either to microdomain-rich regions like Pd (Pd GPI-APs) or other regions (non-Pd GPI-APs). The Pd-associated callose-modifying GPI-APs accumulate in the cell wall domain of Pd through interaction of their ectodomains with a Pd component (e.g. callose). The non-Pd GPI-APs are distributed uniformly at the cell surface both as membrane-anchored and as released cell wall proteins.