Glycosylphosphatidylinositol-Anchored Proteins in Plants

Proteins containing glycosylphosphatidylinositol(GPI) anchors (Fig. 1) are widespread in animal cells [2], where they are highly localized on the outer face of the plasma membrane. There are over 150 different GPI-anchored proteins known, with alkaline phosphatase, acetylcholinesterase, and 5’-nucleotidase being noteworthy as extensively studied examples. Recently their occurrence has been reported in archaebacteria [3] and in the green alga Chlorella saccharophila [4]. In an effort to determine whether higher plants also contain GPI-anchored proteins, we examined the aquatic duckweed Spirodela oligorrhiza because it has been reported [5] to contain alkaline phosphatase, a protein typically GPI-anchored in animals [2].Our work describing a GPI-anchored alkaline phosphatase in S.oligorrhiza [6] represents the first finding of a GPI-anchored protein in higher plants.