Table 1.
The measured Kd (μM) of Cx43 peptides to different forms of ZO-1 PDZ2
| Proteins | Short peptide | Long peptide | Long S(−9)/E | Long S(−10)/E | Long pS(−9) |
|---|---|---|---|---|---|
| Wild type | 16.8±1.1 | 7.2±0.7 | 48.4±2.2 | 18.0±0.4 | >100a |
| K209A mutant | Undetectable | Undetectable | ND | ND | ND |
| R201A mutant | 124.5±6.7 | 136.5±4.3 | ND | ND | ND |
| K191A mutant | ND | 58.6±3.4 | ND | ND | ND |
| K246R mutant | 68.0±2.3 | 35.6±1.2 | ND | ND | ND |
| ND, not determined. | |||||
| aThe binding affinity between the pS(−9) Cx43 long peptide and ZO-1 PDZ2 could not be reliably measured using the same fluorescence polarization assay due to the poor titration curve fitting. The Kd of the peptide was estimated by a competition assay using increasing amount of the pS(−9) Cx43 long peptide to compete with the FITC-labelled Cx43 peptide for ZO-1 PDZ2. In this assay, the concentrations of the FITC-labelled Cx43 peptide and ZO-1 PDZ2 were fixed at a constant concentration. | |||||