X-ray diffraction data from crystals of a novel immune-type receptor (NITR10 from the catfish Ictalurus punctatus) were collected to 1.65 A resolution and reduced to the primitive hexagonal lattice. Native and selenomethionine derivatives of NITR10 crystallized under different conditions yielded P3(1)21 crystals. SeMet NITR10 was phased to a correlation coefficient of 0.77 by SAD methods and experimental electron-density maps were calculated to 1.65 A. Five NITR10 molecules are predicted to be present in the asymmetric unit based on the Matthews coefficient.