Table 2. Summary of cap structures that were cross-validated by 2D-TLC and mass spectroscopy.
| 5′end structure | Name | Known RNAs with thismodification in human | Biological function ofthis RNA | sRNA fraction with thismodification (nt) |
| 2,2,7mGp | N2,N2,7-trimethylguanosine monophosphate | snoRNA | rRNA modification | 20 nt–200 nt |
| 2,2mGp | N2,N2 dimethylguanosine monophosphate | tRNA, rRNA | 20 nt–200 nt | |
| 2,7mGp | N2,7-dimethylguanosine monphosphate | ND | 20 nt–50 nt | |
| 7mGp | 7-methylguanosine monophosphate | tRNA, rRNA, mRNA | 20 nt–50 nt 100 nt | |
| 2mGp | 2-methylguanosine monophosphate | tRNA | 20 nt–200 nt | |
| 1mGp | 1-methylguanosine monophosphate | tRNA, snRNA | translation | 20 nt–50 nt 100 nt |
| Cmp | 2′-O-methylcytidine monophosphate | tRNA, rRNA, snRNA, mRNA | translation, transcription | 20 nt–200 nt |
| Gp | 5′-guanosine monophosphate | All | 20 nt–200 nt | |
| Cp | 5′-cytosine monophosphate | All | 20 nt–200 nt | |
| Ap | 5′-adenosine monophosphate | All | 20 nt–200 nt | |
| Up | 5′-uridine monophosphate | All | 20 nt–200 nt |
*: Unique to this fraction.
**: First time to be reported in mammals.