MAF1

This gene encodes a protein that is similar to Maf1, a Saccharomyces cerevisiae protein highly conserved in eukaryotic cells. Yeast Maf1 is a negative effector of RNA polymerase III (Pol III). It responds to changes in the cellular environment and represses pol III transcription. Biochemical studies identified the initiation factor TFIIIB as a target for Maf1-dependent repression. [provided by RefSeq]

Full Name

MAF1 homolog (S. cerevisiae)

Function

Plays a role in the repression of RNA polymerase III-mediated transcription in response to changing nutritional, environmental and cellular stress conditions to balance the production of highly abundant tRNAs, 5S rRNA, and other small non-coding RNAs with cell growth and maintenance (PubMed:18377933, PubMed:20233713, PubMed:20516213, PubMed:20543138).
Plays also a key role in cell fate determination by promoting mesorderm induction and adipocyte differentiation (By similarity).
Mechanistically, associates with the RNA polymerase III clamp and thereby impairs its recruitment to the complex made of the promoter DNA, TBP and the initiation factor TFIIIB (PubMed:20887893, PubMed:17505538).
When nutrients are available and mTOR kinase is active, MAF1 is hyperphosphorylated and RNA polymerase III is engaged in transcription. Stress-induced MAF1 dephosphorylation results in nuclear localization, increased targeting of gene-bound RNA polymerase III and a decrease in the transcriptional readout (PubMed:26941251).
Additionally, may also regulate RNA polymerase I and RNA polymerase II-dependent transcription through its ability to regulate expression of the central initiation factor TBP (PubMed:17499043).

Biological Process

Negative regulation of transcription by RNA polymerase IManual Assertion Based On ExperimentIDA:CACAO
Negative regulation of transcription by RNA polymerase IIIManual Assertion Based On ExperimentIDA:UniProtKB

Cellular Location

Nucleus
Cytoplasm

PTM

Phosphorylated at Ser-60, Ser-68 and Ser-75; the major sites of phosphorylation. Nuclear accumulation correlates with a concomitant dephosphorylation. Phosphorylation may attenuate its RNA polymerase III-repressive function.
Sumoylated with SUMO1 and SUMO2, mainly on Lys-35. Desumoylated by SENP1. SUMOylation promotes the ability of MAF1 to repress transcription and suppress colony formation.