Backbone and nearly complete side-chain chemical shift assignments reveal the human uncharacterized protein CXorf51A as intrinsically disordered

Even though the human genome project showed that our DNA contains a mere 20,000 to 25,000 protein coding genes, an unexpectedly large number of these proteins remain functionally uncharacterized. A structural characterization of these “unknown” proteins may help to identify possible cellular tasks. We therefore used a combination of bioinformatics and nuclear magnetic resonance spectroscopy to structurally de-orphanize one of these gene products, the 108 amino acid human uncharacterized protein CXorf51A. Both our bioinformatics analysis as well as the ^1 H, ^13 C, ^15 N backbone and near-complete side-chain chemical shift assignments indicate that it is an intrinsically disordered protein.