Functional annotation of newly sequenced genomes:Genome and full-length cDNA sequence projects often include computational (putative) assignments of molecular function based on sequence similarity to annotated genes or sequences. A common tactic now is to use a computational approach to establish some threshold sequence similarity to a SWISS-PROT sequence. Then the GO associations to the SWISS-PROT sequence can be retrieved and associated with the gene model. Under the GO guidelines, the evidence code for this event would be 'inferred from electronic annotation' (IEA).
Functional groupings of gene products:One aspect of the use of the GO for annotation of large data sets is the ability to group gene products to some high level term. For example, while gene products may be precisely annotated as having role in a particular function in carbohydrate metabolism (i.e., glucose catabolism), in the summary documentation of the data set, all gene products functioning in carbohydrate metabolism could be grouped together as being involved in the more general phenomena 'carbohydrate metabolism'. Various sets of GO terms have been used to summarize experimental data sets in this way. The expectation is that published sets of high-level GO terms used in genome annotations and publications will be archived at the GO site. Some of these 'GO slims' are already available.