E1 Ubiquitin Enzymes
Ubiqutin (Ub) - and Ubiqutin-like (Ubl) - dependent metabolism is a multi-enzyme
process involving the continuous activity of different ligases. E1 activating enzymes
are the core of Ub/UBL conjugation in vivo and in vitro, because they initiate
conjugation cascades by activating their respective modifiers.
These enzymes are parts of a larger E1-like superfamily of enzymes that include
cysteine, thiamine, molybdenum cofactor (MoCo) and several secondary metabolites
in biosynthesis. The basic catalytic mechanisms of these enzymes involve adenylation
and sulfonyl transfer as well as specific domains and structures to determine the
specificity of substrate binding and other related protein-protein interactions.
Ubiquitin-activating enzymes
Ubiquitin-activating enzymes, also known as E1 enzymes, are the ubiquitin activating
enzymes in ubiquitin- proteasome pathway, which is the first step in catalytic
ubiquitin cascade. It can load the ubiquitin and other protein ubiquitin samples to
the target protein. This pathway is very important in human tissue cells which can do
the energy dissipation and degradation to specific proteins. Covalent binding of
ubiquitin or ubiquitin-like proteins to target proteins is the main mechanism
regulating protein function in eukaryotes. Many processes such as cell division,
immune response and embryonic development are also regulated by
post-translational modifications of ubiquitin and ubiquitin-like proteins.
