It was a humbling experience, but humility quickly gave way to awe with the realization that the human genome might encode 100,000 to 200,000 proteins. The human genome sequence, particularly its repetitive nature, also rejuvenated interest in genetic mechanisms that underlie the evolution of biological complexity. Eukaryotes, with their myriad cell organelles and other compartments, are far more complex than the evolutionarily much older bacteria and archaeans.
Recent research reveals a number of strategies for genome economy, and some are indeed surprising.
This discovery spawned the idea that a 'split' gene can encode more than one protein by splicing together alternate exon combinations. In effect, the cell shuffles exons, assembling a winning protein hand from assorted cards in its genetic deck. At least 10,000 human genes mix and match exons that encode specific protein regions, or domains. 3 Even exons from different genes can come together. Tissue plasminogen activator, for example, is cobbled together from gene parts that encode plasminogen, epidermal growth factor and fibronectin.