Figure 5.

Suc gradient flotation reveals that the N-terminal 362 amino acids of SUS1 bind to plant membranes. Equal amounts (0.18 pmol μL⁻¹) of full-length SUS1 or the truncation mutant listed above the sections were mixed with equal amounts of basal leaf microsomes at pH 5.5 and 150 mm Suc. After pelleting the microsomes and removing aliquots of the supernatants (input) the pellets were subjected to Suc gradient flotation and the top fraction probed on immunoblots (IB) with an antibody against MBP. Densitometry of these blots is displayed in the graph at the bottom. Note that free MBP did not bind to membranes.