protein geranylgeranyltransferase activity geranylgeranyltransferase type III activity https://github.com/geneontology/go-ontology/issues/29942 Catalyzes the covalent addition of a geranylgeranyl group to a mono-farnesylated substrate via a thioether linkage to a cysteine residue located within a conserved C-terminal tandem cysteine motif (CCAIM or CCIIM) that is used in substrate recognition. Known substrates include mono-farnesylated Golgi SNARE proteins. GO:0170068 2025-03-21T18:53:57Z GGTase-3 activity GGTase-III activity molecular_function ew Geranylgeranyl transferase type-3 activity GGTase3 activity geranylgeranyltransferase type 3 activity