Human interleukin 4 is a glycosaminoglycan-binding protein.
Using different binding assays we examined the interaction of the cytokine interleukin 4 (IL-4) with basement membrane. Equilibrium binding analysis revealed a high-affinity site characterized by a dissociation constant (Kd) of 0.3 nM. This interaction was confirmed by native polyacrylamide gel electrophoresis, which also indicated that the binding sites are composed of glycosaminoglycans (GAGs). In competition studies, N-sulfated GAGs (heparin and heparan sulfate) displayed a higher affinity than other GAGs for IL-4, and therefore may constitute the physiological ligand. Furthermore, the enzymatic and chemical cleavage of heparan sulfate demonstrated that only few peculiar domains (i.e. N-sulfated rich sequences) within heparan sulfate chains, displayed a significant affinity for IL-4. These data indicate a possible role of GAGs in storing IL-4 and modulating the cellular response to this cytokine.
Lortat-Jacob
H
H
Institut Pasteur de Lyon, CNRS, URA 1459, France.
Garrone
P
P
Banchereau
J
J
Grimaud
J A
JA
D001485:Basement Membrane / Q000378:metabolism; D001672:Biocompatible Materials / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D004338:Drug Combinations; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D015847:Interleukin-4 / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism
D001672:Biocompatible Materials; D004338:Drug Combinations; D006025:Glycosaminoglycans; D007797:Laminin; D011509:Proteoglycans; C059485:matrigel; D015847:Interleukin-4; D003094:Collagen