As mentioned in the previous Root Nodes post, there are some terms that have special usage notes. One of these is a tag indicating terms should not be directly annotated to. This usage note is added by including the term in a
do_not_annotate subset. Often, this label is attached to terms that are not incredibly informative on their own, but might be essential for grouping in order to organize the ontology.
Although these notes are primarily intended for curators and tool developers, they can be helpful to users performing term enrichment as a flag that the GO term may not be as informative as other terms. These subset tags can be found in the ontology files, or on a term browser like AmiGO (shown below), QuickGO, or OLS. Be sure to check both Comments and Subsets fields depending on the source you are viewing.
In the below Ancestor Chart obtained from the QuickGO browser, the children of
GO:0005488 binding are displayed. You can see what a difference even this one term makes to organize the ontology. As of the latest GO release,
GO:0005488 binding has 27 child terms- one of these may be much more descriptive and better to use when reporting enrichment results.