FIGURE 5.

SFR2 has only one transmembrane domain. A, immunoblots of A. thaliana wild type or sfr2 protein extracts were probed with antisera raised against the N- or C-terminal amino acids of SFR2, as indicated. Asterisks indicate the location of SFR2. B, emission profile of AlexaFluor 488-labeled secondary antibody labeling chloroplasts decorated with antisera against SFR2 C terminus. Excitation wavelength is 488 nm. C, fluorescence micrographs of chloroplasts incubated first with antisera against the N or C terminus of SFR2 and then in a secondary antibody labeled with AlexaFluor 488. Numbers of chloroplasts present per panel is indicated by chlorophyll fluorescence. Magnifications shown are identical. D, immunoblots detected with antisera indicated at left of chloroplasts isolated from wild type or sfr2 A. thaliana and treated with or without thermolysin in the final concentrations (μg/ml) indicated and with or without the presence of digitonin in percentages indicated. Black arrowheads indicate regions of protein partially resistant to thermolysin.