GLYCOSYL-PHOSPHATIDYLINOSITOL-ANCHORED PROTEINS EXIST IN THE PLASMA-MEMBRANE OF CHLORELLA-SACCHAROPHILA (KRUGER) NADSON - PLASMA-MEMBRANE-BOUND NITRATE REDUCTASE AS AN EXAMPLE

Experiments with plasma-membrane vesicles were performed in order to i dentify the attachment of hydrophobic nitrate reductase at the plasma membrane of Chlorella saccharophila. The enzyme was successfully remov ed from the plasma membrane with phosphoinositol-specific phospholipas e C, and showed cross-reactivity with a monoclonal antibody (clone aGP I-3) raised against the glycosyl-phosphatidylinositol (GPI) anchor of Trypanosoma variant surface protein. The enzyme was labelled in vivo b y feeding [H-3]ethanolamine to the cells and underwent an hydrophobici ty shift after treatment with phosphoinositol-specific phospholipase C , The attachment of this form of nitrate reductase to the plasma membr ane via a GPI anchor was demonstrated.