Harvesting GPI-Anchored Proteins From CHO Cells

Glycosyl-phosphatidylinositol (GPI)-anchored proteins bound to the outer surface of cell membranes (1 ,2 ) can be selectively released in a soluble form by the action of a highly specific bacterial enzyme, phosphatidylinositol-phospholipase C (PI-PLC) (3 ,4 ). This chapter describes a controlled release process (5 –7 ) that increases both the concentration and purity of harvested GPI-anchored proteins by separating the harvesting of the protein from cell growth and protein expression. This approach has obtained product concentrations of up to 500 μg/mL at purities of 35% total protein (5 ,7 ).