High impact information on UBC

• These findings support a model in which an Mms2p/Ubc13p complex assembles novel polyubiquitin chains for signaling in DNA repair, and they suggest that UEV proteins may act to increase diversity and selectivity in ubiquitin conjugation [1].
• Sequence analysis showed them to encode the bovine polyubiquitin (A4), elongation factor 1alpha (B2), the acidic ribosomal phosphoprotein PO (C3), and the ribosomal protein S2 (E10) [2].
• In vitro studies show that E3alpha forms lysine 48-linked polyubiquitin degradation signals on type 1-3 substrates and is absolutely dependent on Ubc2/Rad6 orthologs [3].
• Cyclization of polyubiquitin by the E2-25K ubiquitin conjugating enzyme [4].
• We show that rabbit reticulocyte lysate harbors enzymatic components that catalyze the assembly of unanchored Lys-29-linked polyubiquitin chains [5].

Biological context of UBC

• In this report, we present the results of analyzing the nucleotide sequence of polyubiquitin genes of mammals, available in the DDBJ/EMBL/GenBank nucleotide sequence databases, in which we found that there are two groups of polyubiquitin genes in an orthologous relationship [6].
• Although the predicted amino acid sequence of the ubiquitin from E. histolytica differs significantly (in 7-9 amino acid residues) from that of yeast and animals, expression of the coding sequence of EhUBI1 suppressed the heat-sensitive phenotype of a polyubiquitin gene-deficient yeast mutant [7].

Associations of UBC with chemical compounds

• E2/E3-mediated assembly of lysine 29-linked polyubiquitin chains [5].
• Fluorescent labeling of the six cysteines in the ovomucoid moiety (OM) with Lucifer Yellow iodoacetamide yields UbOM(LY); the ubiquitin in the fusion protein can be extended by the addition of a K48-linked polyubiquitin chain to form Ub(n)OM(LY) [8].

Enzymatic interactions of UBC

• The mammalian ubiquitin conjugating enzyme known as E2-25K catalyzes the synthesis of polyubiquitin chains linked exclusively through K48-G76 isopeptide bonds [9].

Analytical, diagnostic and therapeutic context of UBC

• One of these, EhUBI1, was cloned and sequenced and found to correspond to a monoubiquitin gene; as shown by a polymerase chain reaction, E. histolytica lacked polyubiquitin genes altogether [7].

References