PRotein Ontology (PRO) Release 20.0 (27-Jun-2011) There are 27275 PRO terms 4 terms are in the 'organism-family' category. 304 terms are in the 'family' category. 18205 terms are in the 'gene' category. 1373 terms are in the 'sequence' category. 5926 terms are in the 'modification' category. 99 terms are in the 'complex' category. 435 terms are in the 'organism-gene' category. 380 terms are in the 'organism-sequence' category. 260 terms are in the 'organism-modification' category. 168 terms are in the 'organism-complex' category. 9 terms are in the 'union' category. 1559 terms have some kind of annotation, codifying the information from 1047 papers. 2321 connections to GO (788 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.