Proteomics - Limitations of Genomics and Proteomics Studies

Limitations of Genomics and Proteomics Studies

Proteomics typically gives us a better understanding of an organism than genomics. First, the level of transcription of a gene gives only a rough estimate of its level of expression into a protein. An mRNA produced in abundance may be degraded rapidly or translated inefficiently, resulting in a small amount of protein. Second, as mentioned above many proteins experience post-translational modifications that profoundly affect their activities; for example some proteins are not active until they become phosphorylated. Methods such as phosphoproteomics and glycoproteomics are used to study post-translational modifications. Third, many transcripts give rise to more than one protein, through alternative splicing or alternative post-translational modifications. Fourth, many proteins form complexes with other proteins or RNA molecules, and only function in the presence of these other molecules. Finally, protein degradation rate plays an important role in protein content.

Reproducibility. Proteomics experiments conducted in one laboratory are not easily reproduced in another. For instance, Peng et al. have identified 1504 yeast proteins in a proteomics experiment of which only 858 were found in a similar previous study. Further, the previous study identified 607 proteins that were not found by Peng et al. This translates to a reproducibility of 57% (Peng vs. Washburn) to 59% (Washburn vs. Peng).