TABLE 3.
Binding and signaling parameters for α-factor to strains overexpressing or lacking Sst2p
| Full-length STE2 allele | Sst2p expression levela | Yeast strain | Binding to Lys7-NBD-α-factor |
FUS1-lacZ induction in response to α-factor |
||
|---|---|---|---|---|---|---|
| Kd | Relative Bmaxb | EC50 | Relative Maximal inductionc | |||
| nm | nm | |||||
| Repressed GAL1-STE2 | Chromosomal | A4754 | NDd | ND | 13 ± 1 | 0.9 ± 0.08 |
| Overexpression | A4755 | ND | ND | 23 ± 10 | 0.2 ± 0.03 | |
| Chromosomal | sst2-Δ | A5259 | ND | ND | 0.06 ± 0.02 | 1c |
| Chromosomal | A818 | 15 ± 11 | 1 | 55 ± 20 | 1c | |
| Overexpression | A4757 | 24 ± 22 | 1.3 ± 0.8 | 165 ± 37 | 0.5 ± 0.03 | |
| CEN-STE2 | sst2-Δ | A5260 | ND | ND | 0.13 ± 0.01 | 0.9 ± 0.2 |
| Chromosomal | A4648 | 3 ± 0.3 | 2.5 ± 1 | 41 ± 8 | 1.3 ± 0.1 | |
| Overexpression | A4744 | 7 ± 0.8 | 5.8 ± 2 | 325 ± 50 | 1 ± 0.1 | |
| Multicopy STE2 | sst2-Δ | A5261 | ND | ND | 0.17 ± 0.04 | 0.8 ± 0.2 |
| Chromosomal | A4650 | 7 ± 0.1 | 9 ± 4 | 43 ± 8 | 0.9 ± 0.04 | |
| Overexpression | A4746 | 8 ± 0.7 | 12 ± 5 | 156 ± 39 | 0.5 ± 0.02 | |
a The strains overexpressing Sst2p have a CEN plasmid expressing Sst2p under the constitutive ADH promoter.
b The relative Bmax = Bmax of the strain/Bmax of the strain expressing chromosomal Ste2p, chromosomal Sst2p; Bmax for strain A818 (chromosomal Ste2p, chromosomal G protein) = 12 ± 5 nm; n = 3.
c The relative maximal induction for SST2+ and SST2 overexpressing strains is shown as the maximal induction of the strain/maximal induction of strain A818 expressing chromosomal Ste2p and chromosomal Sst2p. Maximal induction for sst2-Δ strains is shown as the maximal induction of the strain/maximal induction of sst2-Δ strain A5259 expressing chromosomal Ste2p.
d ND means not determined.