differential glycosylation

There are plenty of examples of glycoproteins that _lose_ their activity or
specificity when they are deglycosylated or expressed in bacteria, but can
anyone tell me of specific proteins that _change_ their funtion under
different glycosylation patterns.  For example, a ligand that specifically
binds one receptor when glycosylated and another when not glycosylated.
 
Responses posted to the group would be fine.
Thanks