Beschreibung:
<jats:title>Abstract</jats:title><jats:p>We investigated multiple forms of rabies virus matrix (M) protein. Under non‐reducing electrophoretic conditions, we detected, in addition to major bands of monomer forms (23‐ and 24‐kDa) of M protein, an M antigen‐positive slow‐migrating minor band (about 54 kDa) in both the virion and infected cells. Relative contents of the 54‐kDa and monomer components in the virion were about 20–30% and 70–80% of the whole M protein, respectively, while the content of the 54‐kDa component was smaller (about 10–20% of the total M protein) in the cell than in the virion. The 54‐kDa components could be extracted from the infected cells with sodium deoxycholate, but they were quite resistant to extraction with 1% non‐ionic detergents by which most monomer components were solubilized. The 54‐kDa component was precipitated more efficiently than the monomer by a monoclonal antibody (mAb; #3‐9‐16), which recognized a linear epitope located at the N‐terminal of the M protein. The mAb #3‐9‐16 coprecipitated the viral glycoprotein (G), which was demonstrated to be due to strong association between the G and 54‐kDa component of the M protein. Monomers and the 54‐kDa polypeptide migrated to the same isoelectric point (pI) in two‐dimensional (2‐D) gel electrophoresis, implicating that the 54‐kDa component was composed of component(s) of the same pI as that of the M protein monomers. From these results, we conclude that the M antigen‐positive 54‐kDa polypeptide is a homodimer of M protein, taking an N‐terminal‐exposed conformation, and is strongly associated with the viral glycoprotein. Possible association with a membrane microdomain of the cell will be discussed.</jats:p>