The function of MTFP1 (mitochondrial fission process 1, Ensembl gene identifier ENSG00000242114) is as follows. Plays a role in the regulation of mitochondrial morphology (PubMed:15155745, PubMed:15985469). Inhibits mitochondrial fusion by creating a non-fusogenic lipid environment which affects OPA1 oligomerization and its subsequent capacity to drive fusion (PubMed:38851188). This prevents defective inner mitochondrial membrane (IMM) subdomains from fusing with other mitochondria, facilitating their segregation into small MTFP1-enriched mitochondria (SMEM) which are targeted for autophagic degradation (PubMed:38851188, PubMed:41398051). This IMM quality control mechanism controls mitochondrial DNA levels (PubMed:38851188). {ECO:0000269|PubMed:15155745, ECO:0000269|PubMed:15985469, ECO:0000269|PubMed:38851188, ECO:0000269|PubMed:41398051}.