Figure 2.

COB Is Plasma Membrane–Localized, GPI-Anchored, and N-Glycosylated.

(A) Protein blot probed successively with anti-COB, anti-cytochrome b₅, and anti-ATPase antibodies. Total membrane proteins (TM) were phase-partitioned into endomembranes (DEX) and plasma membrane–enriched protein fractions (PEG).

(B) Protein blot probed successively with anti-COB and anti-cytochrome b₅ antibodies. Proteins associated with total membranes were solubilized in Triton X-114 and phase-partitioned into an aqueous peripheral protein fraction (PP) and a detergent phase (D). The pure detergent phase was treated with PI-PLC (+) or with a buffer (−) and phase-partitioned into new detergent (D) and aqueous phases (A).

(C) Protein blot probed with anti-COB antibodies. Root extracts (RE) or microsomal membranes (M) were incubated with peptide N-glycosidase F (+) or buffer (−), and proteins were separated by SDS-PAGE.

Molecular weights are indicated at right.