Figure 7.
SXD1 Localizes To and Is Imported into Chloroplasts.
(A) Anti-SXD1 antiserum recognizes a 46-kD protein in wild-type (WT) but not sxd1 leaf protein extracts. Soluble proteins were extracted by homogenization without detergent. The insoluble fraction represents the proteins and organelles pelleted by centrifugation of the homogenized tissue and then solubilized in SDS PAGE sample buffer.
(B) Protein gel blots of total leaf proteins (T) versus chloroplast proteins (CP). The same samples were used for detection of SXD1, RBCL, and PEPCase. PEPCase is a cytoplasmic protein, and RBCL resides in the chloroplast stroma.
(C) Import of SXD1 into isolated pea chloroplasts. In vitro–translated 35S-labeled full-length SXD1 protein (lane 1) was incubated with pea chloroplasts under conditions favoring import. The chloroplasts were then untreated (lane 2) or treated with protease (lane 3) or with protease and Triton X-100 to disrupt the chloroplast envelope (lane 4).