Figure 2. Biochemical characterization of sunflower transport percoll vesicles (PV, part a) and sucrose vesicles (SV, part b) fractionated from immature seeds at stages I2 and I3. Presence of proglobulins was analyzed under non reducing conditions with a serum specific to sunflower 11S globulins (11S). Association with the chaperon BiP was analyzed with BiP specific antibody. Sera specific to tonoplast intrinsic proteins α and δ (α-TIP and δ-TIP) were used to characterized the nature of transport vesicles (vacuolar markers). Association of proglobulins with the chaperon BiP was evaluated with BiP specific sera. The presence of vacuolar sorting receptors in PV and SV was studied with sera specific to Arabidposis, pumpkin and pea vacuolar sorting receptors (At-ELP, PV 72 and BP-80 sera, respectively, Part c) Endosplasmic reticulum (microsomes, M) and protein storage vacuoles (PSV) isolated from mature seeds were used as controls. Molecular weight markers (kD) are shown on the left.