PRotein Ontology (PRO) Release 13.0 (14-Aug-2010)

There are 25700 PRO terms
  281 terms are in the 'family' category.
  18184 terms are in the 'gene' category.
  1153 terms are in the 'sequence' category.
  5662 terms are in the 'modification' category.
  144 terms are in the 'organism-gene' category.
  112 terms are in the 'organism-sequence' category.
  38 terms are in the 'organism-modification' category.
  13 terms are in the 'complex' category.
  9 terms are in the 'organism-complex' category.
1439 terms have some kind of annotation, codifying the information from 929 papers.
 2006 connections to GO (688 PRO terms).
 361 connections to MOD (317 PRO terms).
 599 connections to Pfam (358 PRO terms).
 325 connections to SO (307 PRO terms).
 296 annotations of a phenotype (289 PRO terms).

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