Figure 6.

cpTatC Proteins with Cys Residues in S1, S2, L1, or L3 Form Disulfide Linked Dimers.

Radiolabeled precpTatC with three endogenous Cys residues (lane 1) and precpTatCaaa variants with a single Cys substitution at varying positions as indicated were imported into chloroplasts. Recovered thylakoids were washed in DTT-free buffer (top panel) or treated with the oxidant CuP to promote disulfide bond formation (middle panel) or subjected to cross-linking with BM(PEO)3 (bottom panel) and then analyzed by nonreducing SDS-PAGE and fluorography. The different protein species are indicated to the right of the panels.