Figure 4.

Time course of 5-ALA-derived pigment accumulation in dark- and light-incubated etiochloroplasts, respectively. Etiochloroplasts were prepared as described and treated with 5-ALA (A and B) or ³H-5-ALA (C and D) in darkness (A and C) or white light (B and D). Stromal proteins recovered after different stages of import by immunoprecipitation with the pPORA and LHCII antisera, respectively (see Figs. 1 and 2), were extracted with 100% acetone and analyzed by room temperature fluorescence measurements, at an excitation wavelength of 440 nm (A and B), or by liquid scintillation counting (C and D). The different curves show PORA-extracted (A) and FCBP-extracted (B) pigments accumulating at time zero (dotted line) and after 2 min (hatched line), 5 min (solid line), 10 min (stippled line), and 15 min (long dashes) of import. Bars in C and D show ³H-pigments extracted from PORA and FCBP at the indicated stages of import, expressed as percentages of maximum levels.