HIR1, HIR2 and HIR3 are repressors of histone gene transcription. They are required for the periodic repression of three of the four histone gene loci during cell cycle as well as for autogenous regulation of the HTA1-HTB1 locus by H2A and H2B. Also has a role in nucleosome assembly. Component of the HIR complex, composed of HIR1, HIR2, HIR3 and HPC2 (PubMed:16264190, PubMed:16303565). This complex may consist of one copy of HIR1 and HIR3 and two copies of HIR2 and HPC2 (PubMed:16264190). The HIR complex interacts with ASF1 (PubMed:16303565). Interacts with RTT106 (PubMed:19683497). Localizes to the promoter region of histones HTA1-HTB1. Abolishes localization of RTT106 to the HTA1-HTB1 promoter. Present with 922 molecules/cell in log phase SD medium. Belongs to the HIR3 family.