E1 Ubiquitin Enzymes

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.