Western blot analysis of proteins of tomato tissues with antibodies against the GPR product of the tomPRO1 locus. Extracts of the indicated tomato tissues were subjected to electrophoresis on 4–20% polyacrylamide gradient SDS gels and probed with polyclonal antibodies against GPR. Antibodies were obtained from eggs of a chicken that was injected with a highly purified preparation of GPR, synthesized in E. coli from the tomPRO1–1 clone as a 44-kDa product. Lanes: 1 (S15 cells), proteins from tissue culture cells (cv. VFNT Cherry) adapted to 15 g/liter NaCl; 2–6, proteins from the indicated tissues of tomato plants (cv. Rutgers); 7, negative control, containing an extract of E. coli strain JM109 (21); and 8, positive control, containing extract from a derivative of strain JM109 carrying the tomPRO1–1 clone on pKSII+. Lanes 1–4 and 6 were loaded with 25 μg protein, lane 5 with 5 μg protein, and lanes 7 and 8 with 0.5 μg protein. The specific immunoreactive 70-kDa protein (lane 1), 60-kDa protein (lanes 2–5), and 44-kDa protein (lane 8) were absent when the extracts were probed with pre-immune antibodies (data not shown).