MTERF2 (mitochondrial transcription termination factor 2) is a mitochondrial matrix protein that regulates mitochondrial gene expression through multiple mechanisms. MTERF2 binds to mitochondrial DNA throughout the entire genome and specifically to the mtDNA promoter region, where it modulates transcription initiation 1 2. The protein functions as both a positive and negative regulator of mitochondrial transcription, with overexpression leading to inhibition of mtDNA replication, mRNA transcription, and mitochondrial protein translation 2. MTERF2 works in coordination with other MTERF family members (MTERF1 and MTERF3) at the same mtDNA promoter site to fine-tune oxidative phosphorylation function 1. Loss of MTERF2 function results in decreased mitochondrial transcripts, imbalanced tRNA pools, reduced OXPHOS protein levels, and impaired respiratory function, leading to myopathy and memory deficits in mouse models 1. The protein also contributes to mitochondrial dysfunction in neurodegenerative diseases, as MTERF2 expression is elevated in response to MPP+ treatment and contributes to mitochondrial disruption and cell damage 3. In cancer contexts, MTERF2 expression levels have prognostic significance, with high expression associated with improved survival in non-small cell lung cancer patients 4.