Crystallization and preliminary X-ray diffraction studies on the catalytic domain of the chick retinal neurite-inhibitory factor CRYP-2

The receptor protein tyrosine phosphatase CRYP-2 has been shown to be an inhibitory factor for the growth of retinal axons in the chick. The extracellular receptor domain of CRYP-2 contains eight fibronectin repeats and studies using the extracellular domain alone demonstrated the chemorepulsive effect on retinal neurons. The precise role of the intracellular catalytic domain and the mechanism by which its activity is regulated is not known. Determination of the structure of the catalytic domain of CRYP-2 was proposed in an effort to understand the downstream signal transduction mechanism in this system. The cloning, expression, purification and crystallization of the catalytic domain of CRYP-2 are now reported. Preliminary crystallographic studies were performed on the diamond-shaped crystals, which grew under oil using the microbatch method at 298 K. Native X-ray diffraction data were collected to 2.9 Å resolution on a home source. The crystals belong to the trigonal space group P3₁21, with unit-cell parameters a = b = 68.26, c = 244.95 Å. Assuming the presence of two molecules per asymmetric unit, the V_M value was 2.7 Å³ Da^-1 and the solvent content was 54.8%.