Orphan protein function and its relation to glycosylation

Since the first bacterial genomes were completely sequenced, the surge in genome sequence data has overwhelmed the scientific community’s efforts towards elucidating protein function. Computational methods have made it possible to work with sequences from complete genomes and proteomes, and inference of protein function by exploiting direct sequence similarity indeed goes a long way in describing a proteome’s functional capacity.

However, at least 40% of the gene products in newly sequenced genomes typically remain uncharacterised. Proteins without an annotated function are also known as orphan proteins since they do not belong to a functionally characterised protein family. Many sequences must, therefore, be compared using their features rather than by direct comparison in the conventional sequence space.

Here we focus on one such feature — glycosylation — that is common in eukaryotic proteomes