Shotgun Annotation (read more here)
Capturing Biological Complexity. “Shotgun Annotation” captures the known biological complexity available in the UniProt database. From one base gene, many protein products can be formed. Variation arises from different splice forms, coding polymorphisms and post-translational modifications. All of this complexity is captured in our proteome databases.
Database Searching Using Shotgun Annotation (read more here)
To search Top Down data, the intact mass of a protein is queried against our Shotgun Annotated proteome database to select a subset of the total proteins in the database. For each of these candidates, a Poisson-based expectation score is calculated by comparing the predicted protein fragments with the observed fragments.