Human MxA/Mx1 Antibody

MxA (orthoMyxovirus-resistant protein A; also IFN-induced protein p78/IFI-78K and Mx1) is a 75-78 kDa member of the Dynamin family, GTPase-binding superfamily of proteins.  It is induced by type I and III interferons, and is known to reside in the cytoplasm and associate with the membranes of the ER.  Typically, IFN-alpha is produced when influenza virus RNA (plus other viral dsDNA and RNA) is detected by internal Pattern recognition receptors (PRRs).  IFN-alpha induces the synthesis of 300+ genes, one of which is MxA (Mx1 in mouse).  In primates, MxA is cytoplasmic, and interacts with the influenza virus replication cycle at a point proximal to the transcription of genomic RNA into mRNA. By contrast, Mx1 in mouse acts in the nucleus to block primary viral gene transcription.  Functionally, MxA is a GTPase, but it is only the binding of GTP to MxA that is associated with antiviral activity.  Nucleotide binding to MxA is also associated with nonviral activity, being associated with the potentiation of TRPC Ca²⁺ channel activity.  Human MxA is 662 amino acids (aa) in length.  It contains one GTPase domain (aa 69-340) and a GED (GTPase Effector Domain) over aa 574-662.  There are two ultilized phosphorylation sites at Tyr129 and Tyr451.  MxA forms homo-dimers, -tetramers and -oligomers, with multimerization suggested to be important for activity.  Although IFNs are typically considered to induce Mx gene expression, HSV-1 itself also activates gene transcription.  In this case, however, a truncated 54-57 kDa transcript is generated that contains an 84 aa substitution for aa 425-662. Over aa 412-630, human MxA shares 49% aa sequence identity with mouse Mx1.