Crystallization and preliminary X-ray diffraction studies of the guanylate kinase-like domain of PSD-95 protein from rat.

The PSD-95 (postsynaptic density-95) protein, one of the members of the MAGUK (membrane-associated guanylate kinase) family, is composed of three PDZ domains, one SH3 domain and one guanylate kinase-like (GK) domain. The GK domain mediates the scaffolding function of PSD-95 by protein--protein interaction. Here, the GK domain was subcloned, expressed as an intein fusion protein, purified without the intein and then crystallized at room temperature by the hanging-drop vapour-diffusion method using PEG 8000 as a precipitant. The complete native data set was collected to a resolution of 2.35 A using flash-cooling. The crystals belong to the primitive tetragonal space group P4(3) (or P4(1)), with unit-cell parameters a = b = 70.03 (4), c = 37.64 (1) A.