Expression, purification and crystallization of human DOC-1R
人口腔癌症缺失相关蛋白（DOC-1R）的表达、纯化和晶体生长

DOC-1(Deleted in Oral Cancer-1)is a growth suppressor gene identified first in oral cancer.DOC-1R(DOC-1 related)gene is another tumor suppressor gene which was cloned in 1999.Recent studies suggested that DOC-1 and DOC-1R share similarity in both of their sequences and functions.However,there is no homology structure found in PDB.Human doc-1r gene was cloned into expression vector pET-22b( )and over-expressed in E.coli strain BL21(DE3).Human DOC-1R protein was purified in a two-step procedure of Ni-NTA affinity followed by Superdex 75 chromatography.Over 98% of purified DOC-1R proteins was finally got for structural and functional research.Mass Spectrum identified that the exact molecular weight of DOC-1R is 14091.23 Da;Dynamic light scattering assay showed that its homogenesis was over 99.0%.The crystals of DOC-1R were obtained by using hanging-drop vapor-diffusion method.