diff --git a/parsers/SIGNOR/src/signor_mechanism_predicate_mapping.py b/parsers/SIGNOR/src/signor_mechanism_predicate_mapping.py
index bfe8286..dec69e1 100644
--- a/parsers/SIGNOR/src/signor_mechanism_predicate_mapping.py
+++ b/parsers/SIGNOR/src/signor_mechanism_predicate_mapping.py
@@ -71,6 +71,9 @@
 
             # This probably needs to be a node property.
             "guanine nucleotide exchange factor": {
+            	"edge_properties": {
+                                    CAUSAL_MECHANISM_QUALIFIER: "guanyl_nucleotide_exchange"
+		}
             },
 
             "post transcriptional modification": {
@@ -220,4 +223,4 @@
             OBJECT_ASPECT_QUALIFIER: "expression"
         }
     }
-}
\ No newline at end of file
+}