Figure 3.

A stepwise conversion of the 57-kD proRD21 into the 33-kD mRD21 via the 38-kD iRD21. A, The suspension culture of the transformant BY2/RD21 was separated into the cells and the medium. Each 10 μg of total protein from the cells (lane 2) and the medium (lane 3) was subjected to SDS-PAGE followed by immunoblot analysis with anti-RD21 antibodies. The total protein (10 μg) from cells of nontransformant BY2 (lane 1) and the rosette leaves of 20-d-old Arabidopsis plants (lane 4) are also shown on the blot. B, The transformant BY2/RD21 cells were pulse-labeled with [³⁵S] Met and Cys for 1 h (lane 1), and then were incubated with unlabeled Met and Cys for 4 and 12 h (lanes 2 and 3, respectively). The labeled RD21-related proteins were immunoprecipitated with anti-RD21 antibodies. The immunoprecipitates were subjected to SDS-PAGE and were then analyzed with a BAS3000 system. p, proRD21; i, iRD21; m, mRD21. The molecular mass of each marker protein is given on the left in kilodaltons.