Abstract
Synthetic peptides derived from the type I repeats of human platelet thrombospondin containing a consensus sequence Trp-Ser-Xaa-Trp bind to heparin, promote cell adhesion, and inhibit heparin-dependent interactions of melanoma cells with extracellular matrix components (Guo, N. H., Krutzsch, H. C., Nègre, E., Vogel, T., Blake, D. A., and Roberts, D. D. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 3040-3044). In the present study, we further examined the structural requirements for activity of these peptides. The minimal active sequence for heparin or sulfatide binding based on inhibition studies is Trp-Ser-Pro-Trp, although an octapeptide is required for optimal activity. The 2 Trp residues and the Ser residue are essential. Peptides with more than 2 residues between the Trp residues are inactive. The Pro residue is essential for activity of the pentapeptide Trp-Ser-Pro-Trp-Ser, but some larger peptides with substitutions for the Pro residue are active. For direct high affinity binding to heparin, both the consensus sequence and a flanking sequence of basic amino acids are essential. Peptides containing the consensus sequence promote cell adhesion and act cooperatively with the adjacent basic amino acid sequence to promote cell spreading. Chemical modification of the Trp residues in the peptides with amino-terminal basic amino acids abolished both cell adhesion and heparin-binding. Peptides containing the consensus sequence and basic amino acids are chemotactic for A2058 human melanoma cells. The functional importance of this novel heparin and sulfatide-binding motif is suggested by its conservation in other members of the thrombospondin gene family, complement components, and in many members of the cytokine receptor and transforming growth factor beta superfamilies.
Highlights
Synthetic peptides derived from the tyIprepeats of tified in heparin-binding proteins andmay function inligand human platelet thrombospondin containing a consen- binding [1, 2]
Is suggested by its conservation in other members of Recently, we reported thata new class of peptides from the the thrombospondin gene family, complement compo- type I repeats of thrombospondin are strong inhibitorsof the nents, and inmany members of the cytokine receptor and transforming growth factBorsuperfamilies
Tobetterunderstandtheinteractions of thesepeptides chargedsulfate or carboxylate groups inthelatter.Some with sulfated glycoconjugates, we examined the binding to consensus sequences with basic amino acids have been iden- sulfated glycoconjugates of synthetic peptides based on the type I repeats of thrombospondin.Thesestudies provide
Summary
Vol 267, No 27, Issue of September 25. pp. 19349-19355, 1992 Printed in U.S.A. Heparin-binding Peptidesfrom the TypeI Repeats ofThrombospondin STRUCTURALREQUIREMENTSFORHEPARINBINDINGANDPROMOTION ADHESIONANDCHEMOTAXIS*. These activities include melanoma cell spreading [5] and sus sequence and basic amino acidasre chemotactic for chemotaxis [9], binding and internalizatioonf thrombospon-. The bindingof proteins to sulfatedglycoconjugates has ionic characteranddependsontheinteraction of specific positivelychargedresidues intheformerand negatively is located in the three typeI repeats of thrombospondin The importance of this new class of peptide sequences is suggested by its conservation in othermembers of the thrombospondin gene family [29, 30], in some complement components [31], in many members of the cytokine receptor superfamily [32], and in the transformingrowth factor p superfamily [33]. Formance liquid chromatography.Identities of some of the larger peptides, including peptide 246, were verified by complete amino acid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
