Basic transcription factor 3 is a eukaryotic protein that in humans is encoded by the BTF3 gene. They are very important to the development of many eukaryotic organisms such as in humans, plants, fungi, and protists. Some of the functions it plays a part in are gene expression regulation, cell proliferation control, protein homeostasis maintenance, and stress response modulation. BTF3 can be produced in both transcriptionally active and transcriptionally inactive forms through alternative splicing. This helps it to work in multiple cellular compartments and regulatory pathways.
BTF3 evolutionary conservation shows how important its involvement in gene control and cellular homeostasis is. Overtime, it's known for its role in cancer progression and metastasis. This includes gastric cancer, colorectal cancer, pancreatic ductal adenocarcinoma, and nasopharyngeal carcinoma.
More current studies has enhanced our understanding of BTF3 beyond its original designation as a generic transcription factor. Early biochemical studies indicated that BTF3 forms a stable, functional complex with RNA polymerase II, which is required for proper promoter binding and transcription initiation. BTF3 is the β-subunit of the Nascent Polypeptide-Associated Complex (NAC). It attaches to ribosomes at the nascent polypeptide exit tunnel, preventing premature interactions and protein misfolding. This establishes BTF3 as a key regulator of co-translational protein quality regulation.