| MX1 (myxovirus resistance protein 1) is an interferon‑inducible dynamin‑like large GTPase of the innate immune system that acts as a broad antiviral effector downstream of type I and type III interferon signaling and contributes to cell‑intrinsic restriction of diverse RNA and some DNA viruses. The protein contains an N‑terminal GTPase domain, a central bundle‑signaling or stalk region, and a C‑terminal GTPase effector domain, which together support nucleotide binding and hydrolysis, higher‑order oligomerization, and association with intracellular membranes and viral components in a manner typical for the dynamin superfamily. MX1 expression is strongly induced by interferon‑stimulated transcriptional programs and localizes to characteristic cytoplasmic or perinuclear structures where it encounters incoming viral nucleocapsids or ribonucleoprotein complexes and exerts antiviral functions that depend on GTP hydrolysis‑driven conformational changes and assembly into oligomeric scaffolds. Antiviral activity against orthomyxoviruses such as influenza A involves binding to viral ribonucleoprotein complexes and interference with functional assembly of the viral polymerase and nucleoprotein, leading to a block of primary transcription and early replication steps and a sharp reduction in productive infection. MX1 also targets other enveloped and non‑enveloped RNA viruses, including members of bunyaviridae and rhabdoviridae, by interacting with nucleocapsid proteins and altering their trafficking, uncoating, or nuclear import, thereby preventing completion of the replication cycle and reducing progeny virus production. Induction of MX1 expression forms part of a wider interferon‑stimulated gene network, but MX1 makes a non‑redundant contribution to resistance, as its presence defines a barrier to infection by sensitive viruses and its absence or low expression correlates with increased viral replication and more severe disease outcomes in experimental systems and natural infection settings. |
Lane 1: Hela, Lane 2: Hela (hIFN-α1, 100 ng/ml, 16 h)
