Figure 1.

Mutant T60-3 fails to synthesize Rubisco large and small subunits. (A) Pulse labeling of soluble cell proteins in wild-type (lanes 1 and 3) and mutant T60-3 (lanes 2 and 4). Dark-grown cells were labeled with ³⁵SO₄²⁻ for 1 min (lanes 1 and 2) and chased with 10 mM Na₂SO₄ for 1 h (lanes 3 and 4). Equal amounts of radioactivity were fractionated with SDS/PAGE, and protein bands were visualized by fluorography. LS, large subunit; SS, small subunit. (B) Amount of rbcL mRNA in wild-type (lane 1) and mutant T60-3 (lane 2). Total RNA was isolated, resolved in an agarose-formaldehyde gel (10 μg of RNA per lane), and probed with a ³²P-labeled PCR fragment of rbcL (bases 295–1245 relative to the 1428-bp coding region).