22 months ago by
As far as I can tell, an efflux pump complex is something that exists in prokaryotes. You are searching the human annotation package for gene symbols based on a GO term that applies to prokaryotes, so by definition that GO term should not be a valid key (e.g., under the hood you are doing an inner join between the Entrez Gene IDs for human to the respective GO terms. Since that GO term doesn't have a corresponding human Entrez Gene ID, the term is invisible to the org.Hs.eg.db package).
But it does exist in the GO.db package:
> select(GO.db, "GO:1990281", "DEFINITION", "GOID")
'select()' returned 1:1 mapping between keys and columns
1 A protein complex that is capable of efflux transmembrane transporter activity.