Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GDNF (glial cell-line-derived neurotrophic factor), and the closely related cytokines artemin and neurturin, bind strongly to heparin. Deletion of a basic amino-acid-rich sequence of 16 residues N-terminal to the first cysteine of the transforming growth factor beta domain of GDNF results in a marked reduction in heparin binding, whereas removal of a neighbouring sequence, and replacement of pairs of other basic residues with alanine had no effect. The heparin-binding sequence is quite distinct from the binding site for the high affinity GDNF polypeptide receptor, GFRalpha1 (GDNF family receptor alpha1), and heparin-bound GDNF is able to bind GFRalpha1 simultaneously. The heparin-binding sequence of GDNF is dispensable both for GFRalpha1 binding, and for activity for in vitro neurite outgrowth assay. Surprisingly, the observed inhibition of GDNF bioactivity with the wild-type protein in this assay was still found with the deletion mutant lacking the heparin-binding sequence. Heparin neither inhibits nor potentiates GDNF-GFRalpha1 interaction, and the extracellular domain of GFRalpha1 does not bind to heparin itself, precluding heparin cross-bridging of cytokine and receptor polypeptides. The role of heparin and heparan sulfate in GDNF signalling remains unclear, but the present study indicates that it does not occur in the first step of the pathway, namely GDNF-GFRalpha1 engagement.
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PMID:The major determinant of the heparin binding of glial cell-line-derived neurotrophic factor is near the N-terminus and is dispensable for receptor binding. 1729 1

Systemic heparinization, used during haemodialysis to prevent blood clotting on the extracorporeal circuit, leads to a high incidence of hemorrhagic complications. The adverse reactions associated with heparin neutralization using protamine sulphate justify the development of an alternative system for blood deheparinization. The main objective of this work is to design nanostructured surfaces with the capacity to bind heparin from blood in a selective way. A heparin-binding polypeptide, composed of L-lysine and L-leucine (pKL), was synthesized and immobilized, in different concentrations, onto self-assembled monolayers (SAMs) terminated with tetra(ethylene-glycol) (EG4 SAMs). Immobilization was performed using a fixed concentration of pKL after surface activation to different degrees using a range of CDI (N,N'-carbonyldiimidazole) concentrations. Results demonstrated that the presence of pKL increases heparin adsorption to EG4-SAMs, independently of the pKL concentration and the way of immobilization (adsorption or covalent bound). Selectivity towards heparin was successfully achieved on SAMs with low concentrations of immobilized pKL (9-17% of pKL). Surfaces were characterized using ellipsometry, contact angle measurements, Fourier transform infrared reflection absorption spectroscopy (IRAS), atomic force microscopy, and X-ray photoelectron spectroscopy. Heparin adsorption was assessed using IRAS and N-sulphonate-(35)S-heparin. Therefore, this study could give a good contribution for the design of blood deheparinization devices.
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PMID:Molecularly designed surfaces for blood deheparinization using an immobilized heparin-binding peptide. 1828 36

Vitronectin (VN) was isolated and characterized from goat plasma in native and denatured state. Native VN consisted of 160 and >250 kDa polypeptides, whereas denatured VN showed bands of 81 and >250 kDa on SDS-gel. Storage of 81 kDa polypeptide for 3 days at 4 degrees C resulted in formation of 160 and >250 kDa proteins. Hence high molecular weight forms of VN may be dimer and multimeric forms of 81 kDa monomer. Both native as well as denatured VN showed cell adhesive activity. Cells bound to native VN were round, whereas cells adhered to denatured VN were fully spread, a characteristic also observed with 81 kDa polypeptide. The 81 kDa VN bound to Heparin, whereas the 160 kDa preparation did not bind to Heparin in presence of urea. Absence of EDTA resulted in the degradation of goat VN. Similarly, addition of excess Ca(2+) caused total degradation of VN polypeptides in buffers with EDTA, suggesting metalloprotease activity inthe protein.
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PMID:Characterization of goat plasma vitronectin. 2290 Mar 9


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