The matrix protein, M1, of influenza virus strain A/PR/8/34 has been purified from virions and crystallized. The crystals consist of a stable fragment (18 kDa) of the M1 protein. X-ray diffraction studies indicated that the crystals are in space group P3121 or P3221, with a = 66.17, c = 135.30Å. V(m) calculations showed that there are two monomers in the asymmetric unit.
