the last category being split into E1, E2, E3 etc. As with all grades, these categorisations are subjective; there are no cut off points. VS runs smoothly into HVS, HVS runs into E1. Also, some ...

are post-translationally attached to proteins through a sequential enzymatic cascade that uses an E1 activating enzyme, an E2 conjugating enzyme and an E3 ligase. It was presumed that a single E1 ...