  Ubiquitin tags diseased proteins and initiates an enzyme conjugation cascade,
which has three stages. The first-stage enzyme Uba1 (E1) has evolved only
modestly from slime mold to humans, and is > 14 times larger than Ub. Here we
use critical point thermodynamic scaling theory to connect Uba1 (E1) evolution
from yeast and slime mold to fruit flies and humans to subtle changes in its
amino acid sequences.
