Expression, crystallization and preliminary X-ray studies of the recombinant PTB domain of human dok-5 protein

The human dok-5 PTB domain fusion protein has been overexpressed in Escherichia coli and crystallized in a form suitable for X-­ray crystallographic study. Crystals were obtained by the vapour-diffusion method. The crystal has unit-cell parameters a = b = 75.9, c = 108.0 Å, α = β = 90, γ = 120° and belongs to space group P3₂21. Diffraction data were collected to 2.8 Å resolution in-house. Furthermore, a selenomethionine (SeMet) derivative of dok-5 PTB domain fusion protein was overexpressed using the same expression system and was purified in a reductive environment. The derivative crystals were obtained under similar conditions. Subsequently, three different wavelength data sets were collected to 2.3 Å resolution from the derivative crystal at the Advanced Photon Source, Argonne National Laboratory.