TABLE 1.
Most protein labeling sites show no site-specific hydroxyl radical cleavage
The table displays the domain location, the motif, and the amino acid number of cysteine labeling sites used in site-directed hydroxyl radical probing experiments. Cleavage products of site-directed hydroxyl radical probing experiments were compared with those obtained from unlabeled protein and scored based on the observed increase in the intensity of cleavage products (− indicates no observed increase in intensity, ++ indicates moderate to strong cleavage products). Labeling sites in the N-terminal (TEN) domain were obtained with a construct containing residues 1–516 of TERT. We note that a negative probing result does not necessarily preclude the possibility of RNA interactions at this site. A specific labeling site may suffer from poor accessibility to Fe-BABE labeling, or the label itself could prevent the RNA interaction it was intended to measure.
| Location | Labeling site amino acid number | Strength of hydroxyl radical cleavage |
|---|---|---|
| TEN | 61 | − |
| TEN | 77 | − |
| TEN | 129 | − |
| TEN T2 motif | 134 | − |
| TEN T2 motif | 173 | − |
| TEN | 187 | − |
| RBD CP2 motif | 232 | ++ |
| RBD | 260 | − |
| RBD | 283 | − |
| RBD CP motif | 331 | − |
| RBD | 342 | − |
| RBD | 443 | − |
| RBD T motif | 486 | − |
| RBD | 500 | − |