Table 1. Solvent accessibility of cysteine sulfur atoms in Rac1, RhoA, and Cdc42.
| Thiol accessibility (Rac1/Cdc42, RhoA) |
Rac1GTP PDB 3TH5 |
Rac1GDP (Zn-bound) PDB 2P2L |
RhoAGTP PDB 1A2B |
RhoAGDP PDB 1FTN |
Cdc42GTP PDB 2QRZ |
Cdc42GDP PDB 1AN0 |
|---|---|---|---|---|---|---|
| Cys6, NA | 0.0 | 0.0 | NA | NA | 0.0 | 0.0 |
| NA, Cys16 | NA | NA | 0.0 | 0.0 | NA | NA |
| Cys18, Cys20 | 8.7 | 0.0 | 4.1 | 0.0 | 0.0 | 0.0 |
| Cys81, Cys83 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Cys105, Cys107 | 9.8 | 0.56 | 3.9 | 1.9 | 0.0 | 0.05 |
| Cys157, Cys159 | 0.70 | 0.45 | 1.2 | 0.04 | 0.21 | 0.13 |
| Cys178, NA | ND | 35 | NA | NA | 6.0 | 3.7 |
Solvent accessibility (in square angstroms) of cysteine thiol atoms determined using nAccess.107 Numbering in the left column is for Rac1 and Cdc42, with numbering for RhoA listed after the comma. nAccess was executed in the presence of heteroatoms, including the bound nucleotide. Only Cys18 (Cys20) shows differential protection in the presence of nucleotide, displays nucleotide dependence, and increased accessibility in the absence of nucleotide. For comparison, the solvent accessibility of the sulfur atom in an Ala-Cys-Ala tripeptide is ~60 Å2. ND, No data; NA, Not available.