PRotein Ontology (PRO) Release 18.0 (25-Apr-2011)

There are 26879 PRO terms
   304 terms are in the 'family' category.
  18201 terms are in the 'gene' category.
  1343 terms are in the 'sequence' category.
  5896 terms are in the 'modification' category.
   44 terms are in the 'complex' category.
   342 terms are in the 'organism-gene' category.
   343 terms are in the 'organism-sequence' category.
   192 terms are in the 'organism-modification' category.
   93 terms are in the 'organism-complex' category.
    9 terms are in the 'union' category.
1545 terms have some kind of annotation, codifying the information from 1032 papers.
  2282 connections to GO (774 PRO terms).
   374 connections to MOD (327 PRO terms).
   604 connections to Pfam (362 PRO terms).
   338 connections to SO (317 PRO terms).
   306 annotations of a phenotype (299 PRO terms).

The ontology includes a subset of terms from other ontologies and resources that are used for logical definitions.