Table 1. Comparison of proteasome-sensitive and proteasome-insensitive ubiquitination and phosphorylation sites across human protein kinases.
We have separated out the data from HEK293 cells because they may also include some ISG15 modifications.
| Jurkat + PTMfunc | On kinase domain | On any folded domain | Residue conserved | Modification conserved | Near phos. site | Near phos. hot spot |
| % of proteasome-sensitive ubiquitination sites | 52% | 78% | 87% | 55% | 11% | 7% |
| % of proteasome-insensitive ubiquitination sites | 42% | 79% | 81% | 50% | 17% | 5% |
| % of all ubiquitination sites | 47% | 72% | 80% | 48% | 11% | 3% |
| % of phosphorylation sites | 17% | 28% | 59% | 44% | NA | NA |
| HEK293 | On kinase domain | On any folded domain | Residue conserved | Modification conserved | Near phos. site | Near phos. hot spot |
| % of proteasome-sensitive ubiquitination sites | *56% | *80% | 79% | 44% | 12% | 4% |
| % of proteasome-insensitive ubiquitination sites | *36% | *60% | 79% | 33% | 15% | 0% |
| % of all ubiquitination sites | 46% | 68% | 79% | 39% | 12% | 2% |
* indicates a significant difference between the proteasome-sensitive and proteasome-insensitive percentages using the function prop.test in R. A conserved residue is defined as occurring more than 40 times out of 832 kinases, and a conserved modification is defined as occurring more than 5 times. “Near” is defined as within four residues of the ubiquitinated residue. Phosphorylation hot spots are those sites where phosphorylation is believed to play a role in function, as determined by the PTMfunc database. We also have data on the effect of HIV expression on ubiquitination, reported in the supporting information (S2 Table).