High impact information on HIP2

• This reaction can be reconstituted using the ubiquitin-conjugating enzyme (E2) known as UbcH5A, a 120-kDa protein(s) that behaves as a ubiquitin-protein ligase (E3), and ubiquitin-activating enzyme (E1) [1].
• A previously studied species of ubiquitin-protein ligase contains specific sites for the binding of basic (Type I) and bulky hydrophobic (Type II) NH2-terminal amino acid residues of protein substrates [2].
• Apart from its different substrate specificity, it resembles E3 alpha in some physical properties, in a requirement for ubiquitin carrier protein (E2) for conjugate formation, and in its action to ligate multiple ubiquitin units to the substrate protein [2].
• Post-translational addition of an arginine moiety to acidic NH2 termini of proteins is required for their recognition by ubiquitin-protein ligase [3].

Anatomical context of HIP2

• Enzyme activities that catalyzed the covalent attachment of ubiquitin to protein substrates (ubiquitin-protein ligase, UbL) were purified from the extracts of human red blood cells [4].

Associations of HIP2 with chemical compounds

• Addition of exogenous E1 resulted in an increase in ubiquitin conjugation activity and in the levels of ubiquitin carrier protein (E2)-ubiquitin thiol esters in both the untreated cells and the H2O2-treated cells [5].
• A 25-kilodalton ubiquitin carrier protein (E2) catalyzes multi-ubiquitin chain synthesis via lysine 48 of ubiquitin [6].

Physical interactions of HIP2

• Recent studies have shown that selection of proteins for degradation by the ubiquitin system occurs most probably by binding to specific sites of the ubiquitin-protein ligase, E3 [3].

Enzymatic interactions of HIP2

• Ubiquitin carrier protein-catalyzed ubiquitin transfer to histones. Mechanism and specificity [7].

Regulatory relationships of HIP2

• Multiple forms of ubiquitin-protein ligase. Binding of activated ubiquitin to protein substrates [4].

References