Figure 3.

Calreticulin proteolysis by cathepsin P.

Western blotting of time-dependent (1, 6 and 20 h) hydrolysis of Rcho-1 proteins by cathepsin P using an antibody to the C-terminus of calreticulin showed a time-dependent reduction of full-length calreticulin (A). No detectable proteolysis of calreticulin was observed in the absence of cathepsin P. The amount of full-length calreticulin was also reduced by increasing amounts of cathepsin P (B). Relative amounts of cathepsin P added to a constant amount of cellular protein are indicated above each lane, 1 representing a protein/enzyme ratio of 250:1. Probing of similar blots using an antibody to the N-terminus of calreticulin shows time-dependent (1, 6 and 20 h) appearance of discreet proteolytic fragments with of 34, 41, 46 and 52 kDa (C). A schematic view of processing of calreticulin is shown in (D). Representative gels of at least three separate experiments are shown.