MARCHF7 (membrane associated ring-CH-type finger 7) is an E3 ubiquitin ligase that regulates multiple cellular processes through substrate ubiquitination. As an E3 ligase, MARCHF7 accepts ubiquitin from E2 conjugating enzymes and transfers it to target substrates 1. MARCHF7 has diverse mechanistic roles: it stabilizes Mdm2 through Lys63-linked polyubiquitination, thereby suppressing p53 and promoting cell proliferation 2; it catalyzes mixed polyubiquitination on ATG14 to inhibit autophagy 3; and it promotes pexophagy by ubiquitinating PXMP4 at lysine 20 in response to peroxisomal dysfunction 4. MARCHF7 also regulates ciliogenesis through differential ubiquitination of NPHP5 5 and ubiquitinates tau protein, impairing microtubule binding in tauopathies 6. Disease relevance includes cancer progression: high MARCHF7 expression correlates with poor prognosis in epithelial ovarian cancer and endometrial cancer, where it promotes invasion and metastasis via Snail-mediated pathways [PMID:27302477; 70]. Clinically, MARCHF7 has antiviral significance—it mediates proteasomal degradation of SARS-CoV-2 nsp16 through K27-linked ubiquitination and interacts with foot-and-mouth disease virus 2C protein [PMID:40358464; 84]. These findings identify MARCHF7 as a multifunctional E3 ligase with therapeutic potential in cancer and infectious diseases.