Title : The isoforms of human neutrophil elastase and cathepsin G differ in their carbohydrate side chain structures
Abstract :
The two proteinases found in human neutrophil granules, elastase and cathepsin G , each are normally isolated as a mixture of isoforms differing only in carbohydrate content
Elastase has two N-glycosylation sites occupied ( Asn-45 and Asn-144 ), whereas cathepsin G has only one ( Asn-64 )
Analysis of a minor form of elastase ( E-1) and cathepsin G ( C-1 ) indicates that the carbohydrate structures at each glycosylation site are complex-type bi-antennary chains usually associated with secretory glycoproteins
In contrast, the isoforms E-3 and C-3 , the major forms of elastase and cathepsin G respectively, contain exclusively truncated, oligomannose-type chains at the same positions in the sequence of each protein
These data suggest the possibility that certain elastase and cathepsin G isoforms (E-1 and C-1 ) might be destined for secretory, others ( E-3 and C-3 ) for lysosomal functions