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Updated: Aug 18, 2026

Monitoring Neutrophil Elastase and Cathepsin G Activity in Human Sputum Samples
Published on: May 21, 2021
Isolation and primary structure of NGAL, a novel protein associated with human neutrophil gelatinase
L Kjeldsen1, A H Johnsen, H Sengeløv
1Departments of Hematology, University Hospital, Rigshospitalet, Copenhagen, Denmark.
Abstract:
A 25-kDa protein was found to be associated with purified human neutrophil gelatinase. Polyclonal antibodies raised against gelatinase not only recognized gelatinase but also this 25-kDa protein. Specific antibodies against the 25-kDa protein were obtained by affinity purification of the gelatinase antibodies. Immunoblotting and immunoprecipitation studies demonstrated the 135-kDa form of gelatinase to be a complex of 92-kDa gelatinase and the 25-kDa protein, and the 220-kDa form was demonstrated to be a homodimer of the 92-kDa protein, thus explaining the 220-, 135-, and 92-kDa forms characteristic of neutrophil gelatinase. The 25-kDa protein was purified to apparent homogeneity from exocytosed material from phorbol myristate acetate-stimulated neutrophils. The primary structure of the 25-kDa protein was determined as a 178-residue protein. It was susceptible to treatment with N-glycanase, and one N-glycosylation site was identified. The sequence did not match any known human protein, but showed a high degree of similarity with the deduced sequences of rat alpha 2-microglobulin-related protein and the mouse protein 24p3. It is thus a new member of the lipocalin family. The function of the 25-kDa protein, named neutrophil gelatinase-associated lipocalin (NGAL), remains to be determined.
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