You can find more information about Xrn1 using the following links:

PFID PFID Old Formal Annotation PlasmoDB TDR Targets Subcellular Localization Affecting Drugs
Drug Name PubMed Articles (year of publication)
PF3D7_0909400 PFI0455w exoribonuclease, putative PlasmoDB TDR
PF3D7_1106300 PF11_0074 5'-3' exoribonuclease 1, putative PlasmoDB TDR
Expasy - NiceZime View
Brenda - The Comprehensive Enzyme Information System