Regulatory protein SIR1

UniProtKB accession:  P21691

Grouped By:  Matching UniProtKB accession

UniProtKB description:  Involved in the establishment, but not the maintenance, of heterochromatic silencing at the cryptic mating-type loci HMR and HML. Is recruited by interacting with the ORC1 subunit of the origin recognition complex (ORC), which binds to HML-I or HMR-E silencers, DNA elements that direct the formation of silent chromatin at the mating-type loci. Establishes transcriptional silencing by recruiting the three other SIR proteins, SIR2, SIR3, and SIR4, that function directly in silenced chromatin and establish repression. Also found in centromeric chromatin. Binds to and helps retain CAC1, a subunit of chromatin assembly factor I (CAF-I) at centromeric loci independent on the other SIR proteins.