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CRYSTAL STRUCTURES OF NK1-HEPARIN COMPLEXES REVEAL THE BASIS FOR NK1 ACTIVITY AND ENABLE ENGINEERING OF POTENT AGONISTS OF THE MET RECEPTOR
[HGF_HUMAN] Defects in HGF are the cause of deafness autosomal recessive type 39 (DFNB39) [MIM:608265]. A form of profound prelingual sensorineural hearing loss. Sensorineural deafness results from damage to the neural receptors of the inner ear, the nerve pathways to the brain, or the area of the brain that receives sound information.
[HGF_HUMAN] Potent mitogen for mature parenchymal hepatocyte cells, seems to be a hepatotrophic factor, and acts as a growth factor for a broad spectrum of tissues and cell types. Activating ligand for the receptor tyrosine kinase MET by binding to it and promoting its dimerization. 
Publication Abstract from PubMed
NK1 is a splice variant of the polypeptide growth factor HGF/SF, which consists of the N-terminal (N) and first kringle (K) domain and requires heparan sulfate or soluble heparin for activity. We describe two X-ray crystal structures of NK1-heparin complexes that define a heparin-binding site in the N domain, in which a major role is played by R73, with further contributions from main chain atoms of T61, K63 and G79 and the side chains of K60, T61, R76, K62 and K58. Mutagenesis experiments demonstrate that heparin binding to this site is essential for dimerization in solution and biological activity of NK1. Heparin also comes into contact with a patch of positively charged residues (K132, R134, K170 and R181) in the K domain. Mutation of these residues yields NK1 variants with increased biological activity. Thus, we uncover a complex role for heparan sulfate in which binding to the primary site in the N domain is essential for biological activity whereas binding to the K domain reduces activity. We exploit the interaction between heparin and the K domain site in order to engineer NK1 as a potent receptor agonist and suggest that dual (positive and negative) control may be a general mechanism of heparan sulfate-dependent regulation of growth factor activity.
Crystal structures of NK1-heparin complexes reveal the basis for NK1 activity and enable engineering of potent agonists of the MET receptor.,Lietha D, Chirgadze DY, Mulloy B, Blundell TL, Gherardi E EMBO J. 2001 Oct 15;20(20):5543-55. PMID:11597998
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.