The function of Ensembl gene identifier ENSG00000140691 (ARMC5, armadillo repeat containing 5) is as follows. Substrate-recognition component of a BCR (BTB-CUL3-RBX1) E3 ubiquitin ligase complex that terminates RNA polymerase II (Pol II) transcription in the promoter-proximal region of genes (PubMed:39504960, PubMed:39667934). The BCR(ARMC5) complex provides a quality checkpoint during transcription elongation by driving premature transcription termination of transcripts that are unfavorably configured for transcriptional elongation: the BCR(ARMC5) complex acts by mediating ubiquitination of Pol II subunit POLR2A phosphorylated at 'Ser-5' of the C-terminal domain (CTD), leading to POLR2A degradation (PubMed:35687106, PubMed:38225631, PubMed:39504960, PubMed:39667934). The BCR(ARMC5) complex acts in parallel of the integrator complex and is specific for RNA Pol II originating from the promoter-proximal zone: it does not ubiquitinate elongation-stalled RNA Pol II (PubMed:39667934). The BCR(ARMC5) complex also acts as a regulator of fatty acid desaturation by mediating ubiquitination and degradation of SCAP-free SREBF1 and SREBF2 (PubMed:35862218). Involved in fetal development, T-cell function and adrenal gland growth homeostasis (PubMed:24283224, PubMed:28676429). Plays a role in steroidogenesis, modulates steroidogenic enzymes expression and cortisol production (PubMed:24283224, PubMed:28676429). {ECO:0000269|PubMed:24283224, ECO:0000269|PubMed:28676429, ECO:0000269|PubMed:35687106, ECO:0000269|PubMed:35862218, ECO:0000269|PubMed:38225631, ECO:0000269|PubMed:39504960, ECO:0000269|PubMed:39667934}.