Catalysis of the reaction: GTP + protein = diphosphate + guanylyl-protein; mediates the addition of an guanylyl (guanosine 5'-monophosphate; GMP group) to specific residues of target proteins. [ GOC:sp http://www.ncbi.nlm.nih.gov/pubmed/20651120 ]
This is just here as a test because I lose it