The function of PHF12 (PHD finger protein 12, Ensembl gene identifier ENSG00000109118) is as follows. Transcriptional repressor acting as key scaffolding subunit of SIN3 complexes which contributes to complex assembly by contacting each core subunit domain, stabilizes the complex and constitutes the substrate receptor by recruiting the H3 histone tail (PubMed:37137925). SIN3 complexes are composed of a SIN3 scaffold subunit, one catalytic core (HDAC1 or HDAC2) and 2 chromatin targeting modules (PubMed:11390640, PubMed:37137925). SIN3B complex represses transcription and counteracts the histone acetyltransferase activity of EP300 through the recognition H3K27ac marks by PHF12 and the activity of the histone deacetylase HDAC2 (PubMed:37137925). SIN3B complex is recruited downstream of the constitutively active genes transcriptional start sites through interaction with histones and mitigates histone acetylation and RNA polymerase II progression within transcribed regions contributing to the regulation of transcription (PubMed:21041482). May also repress transcription in a SIN3A- independent manner through recruitment of functional TLE5 complexes to DNA (PubMed:11390640). May also play a role in ribosomal biogenesis (By similarity). {ECO:0000250|UniProtKB:Q5SPL2, ECO:0000269|PubMed:11390640, ECO:0000269|PubMed:21041482, ECO:0000269|PubMed:37137925}.