Patent ID: 8207114

Claim:
An underglycosylated targeted therapeutic fusion protein comprising: a lysosomal enzyme; and a lysosomal targeting domain that binds an extracellular domain of human cation-independent mannose-6-phosphate receptor in a mannose-6-phosphate-independent manner, wherein the lysosomal targeting domain is mature human IGF-II or a mutein of mature human IGF-II having an amino acid sequence at least 70% identical to mature human IGF-II, and (i) does not bind a mutein in which amino acid 1572 of the human cation-independent mannose-6-phosphate receptor is changed from isoleucine to threonine; or (ii) binds the mutein with a dissociation constant at least ten times the dissociation constant for binding the extracellular domain of human cation-independent mannose-6-phosphate receptor.