Crystallization and preliminary X-ray analysis of the splice variant of human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9-2).

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9), a subunit of an Elongin C-cullin-SOCS box (ECS) E3 ubiquitin ligase complex, is believed to be involved in specific substrate-recognition for ubiquitination and degradation. In fact, this specific substrate-recognition is determined by the ankyrin repeats of hASB9 protein. Here, we have cloned and overexpressed the hASB9-2, the splice variant of hASB9 with only one ankyrin repeat domain, as a 6His-tagged recombinant protein in Escherichia coli. The purified hASB9-2 protein was crystallized by the hanging-drop vapor-diffusion technique and diffracted to 2.2A resolution. The data showed that the cubic hASB9-2 crystal belongs to space group P4(3)32 with unit-cell parameters (a=b=c=129.25A, alpha=beta=gamma=90 degrees). An asymmetric unit in the crystal was assumed to contain one protein molecule giving the Matthews Coefficient factor of 2.81 and the solvent content of 56.3%.