Figure 3.

Reduced Activity of Altered Forms of PGAP2 in Restoring Surface Expression of GPI-Anchored Proteins after Transfection into PGAP2-Null Cell Lines

PGAP2-deficient CHO cells were transiently transfected with wild-type or altered forms (p.Arg16Trp, p.Thr160Ile [family A], and p.Leu127Ser [family B]) of pTA Flag-PGAP2 isoform 8 driven by a weak promoter. Restoration of the surface expression was assessed 2 days later by flow cytometry. p.Arg16Trp and p.Thr160Ile detected in family A and p.Leu127Ser detected in family B did not restore the surface expression of CD59 and CD55 as efficiently as the wild-type PGAP2. The reduction of surface protein levels associated with p.Arg16Trp was less severe. This correlates with a lower sequence conservation of this position and a milder phenotype in individual II-1of family A.