Table I. Protein expression with different translation and stop contexts.
| Plasmids | Constructions | Gene expression |
Transmission T (3A′/2A′′) | Stop codon effect UAA/UGA | ||
|---|---|---|---|---|---|---|
| 3A′ | 2A′′ | |||||
| pHN52 | SD+-AUG-2A′-CCAUAA A | – | 0.22 ± 0.03 | – | ||
| pHN53 | SD+-AUG-2A′-CCAUGA A | 0.07 ± 0.01 | 0.11 ± 0.01 | 0.64 ± 0.05 | pHN52/pHN53 | 1.2 |
| pHN55 | SD+-AUG-2A′-AGCUAA U | – | 0.25 ± 0.03 | – | ||
| pHN56 | SD+-AUG-2A′-AGCUGA U | – | 0.24 ± 0.02 | – | pHN55/pHN56 | 1.0 |
| pHN58 | SD–-AUG-2A′-CCAUAA A | – | 0.097 ± 0.01 | – | ||
| pHN59 | SD–-AUG-2A′-CCAUGA A | 0.035 ± 0.01 | 0.044 ± 0.01 | 0.80 ± 0.08 | pHN58/pHN59 | 1.2 |
| pHN61 | SD–-AUG-2A′-AGCUAA U | – | 0.105 ± 0.02 | – | ||
| pHN62 | SD–-AUG-2A′-AGCUGA U | 0.104 ± 0.02 | – | pHN61/pHN62 | 1.0 | |
Protein A′ expressed in M9 minimal medium in 1 mM IPTG. The 3A′ values are normalized to 2A′ obtained by correction for the molecular weight of the A′ proteins (Björnsson et al., 1998). All contexts have GAC as the –2 stop codon and DR-A penta-codon sequence downstream of the initiation codon of the SD+ group. The DR-B penta-codon sequence was used in the SD– group. SD+ is AAGGAGG and SD– is AAAUAAA (Figure 3). All data were obtained from at least four independent experiments.