The LD of human RanBP2 (residues 62–711) was subcloned in-frame into the GAL4 DNA-binding domain of bait vector, pBUTE (a kanamycin-resistant version of GAL4 bait vector pGBDUC1) [62] and HybriZAP pBD-GAL4 vector (Stratagene, La Jolla, California, United States). The former was used to screen ~18 million clones via mating from murine 9- to 10-d-old embryo and brain cDNA libraries at the Molecular Interaction Facility (MIF), University of Wisconsin, Madison, Wisconsin. The latter was used to screen via transformation of ~5 million clones from bovine retinal cDNA libraries [32]. The screens generated six clones. One and two in-frame clones were independently isolated from the embryonic and adult brain libraries, respectively, and the interactions were validated. The three clones encoded Cox11. Interactions between Cox11, LD, and subdomains thereof were quantified by liquid β-galactosidase (Applied Biosystems, Foster City, California, United States) and growth assays [63]. The maximum specific growth speed (μmax) was determined by calculating μmax = (ln(x t) − ln(x 0))/t, where x t is the OD600 of the culture at t = t, x 0 is the OD600 at t = 0 and t is the time between x 0 and x t. Assays were performed with three independent clones and three samples of each clone, the results were averaged, and the standard deviations calculated.