Functional sites of glia-derived nexin (GDN): importance of the site reacting with the protease.
Glia-derived nexin (GDN) is a 43-kDa serine protease inhibitor with neurite promoting activity in mouse neuroblastoma cells (Guenther et al., 1985). In chick sympathetic neurons, GDN but not hirudin and synthetic peptide inhibitors promoted neurite outgrowth (Zurn et al., 1988). Thus, it was considered that the protease inhibitory activity cannot account for the total biological activity of GDN. We show here that synthetic peptide inhibitors with thrombin specificity mimic GDN at similar concentrations in neuroblastoma cells. Limited proteolysis of GDN with elastase causes a cleavage between sites P1 and P2, corresponding to residues Ala-344-Arg-345 of the molecule. The resulting fragments still copurify on heparin-Sepharose, but the protease inhibitor activity of GDN and the GDN neurite promoting activity are lost. The results confirm the necessity of an intact reactive site for the biological activity of GDN.
Nick
H
H
Friedrich Miescher Institute, Basel, Switzerland.
Hofsteenge
J
J
Shaw
E
E
Rovelli
G
G
Monard
D
D
D000595:Amino Acid Sequence; D001369:Axons / Q000187:drug effects / Q000648:ultrastructure*; D001665:Binding Sites; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000378:metabolism* / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000494:pharmacology; D009447:Neuroblastoma; D010196:Pancreatic Elastase / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D013917:Thrombin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D011480:Protease Inhibitors; C049173:glia-derived neurite-promoting factor; D010196:Pancreatic Elastase; D013917:Thrombin