Recombinant Saccharomyces cerevisiae Regulator of Ty1 transposition protein 101 (RTT101), partial

Core component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes (CRLs), which mediate the ubiquitination of target proteins. As a scaffold protein may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The CRL associates with CDC34 as the E2 ubiquitin-conjugating enzyme. The functional specificity of the CRL depends on the type of the associated substrate receptor protein. RTT101(MMS1-MMS22) promotes fork progression through damaged DNA or natural pause sites by stabilizing replication proteins like the replication fork-pausing complex (FPC) and leading-strand polymerase at stalled replication forks. RTT101(MMS1-MMS22) ubiquitinates the acetylated histones H3K56ac-H4 at lysine residues H3K121, H3K122 and H3K125. Ubiquitination is required for efficient histone deposition during replication-coupled nucleosome assembly, probably by facilitating the transfer of H3-H4 from ASF1 to other chaperones involved in histone deposition. RTT101(MMS1-CRT10) may regulate nucleotide synthesis through transcriptional regulation of ribonucleotide reductase. RTT101(MMS1) is also involved in the non-functional rRNA decay (NRD) of 25S rRNA through the selective, ubiquitination-dependent degradation of nonfunctional ribosomal particles. Ubiquitinates the FACT (facilitates chromatin transcription) complex subunit SPT16 in an MMS1-independent manner. Involved in regulation of Ty1 transposition and protects the genome from Ty1 integration upstream of tRNA genes.