Cartilage link protein interacts with neurocan, which shows hyaluronan binding characteristics different from CD44 and TSG-6.
The interaction of neurocan with hyaluronan was qualitatively characterized with alkaline phosphatase fusion proteins secreted by mammalian cells. The wild type neurocan hyaluronan binding domain fused to alkaline phosphatase bound to immobilized hyaluronan under physiological as well as moderately hypertonic conditions, whereas its ability to bind to immobilized chondroitin sulfate dropped rapidly with increasing salt concentration. Strong hyaluronan binding ability was still evident when in both link modules within the hyaluronan binding domain a basic amino acid was mutated, which is well conserved among link modules of hyaluronan binding proteins. A strong enhancement of the binding of neurocan to immobilized hyaluronan was observed after preincubation of the immobilized hyaluronan with cartilage link protein. Moreover, this preincubation mediated also the binding of a fusion protein representing only the immunoglobulin module of neurocan linked to alkaline phosphatase, which showed no binding to immobilized hyaluronan alone. The interaction of the neurocan immunoglobulin module with link protein could also be shown by overlay blot analysis. These observations suggest that the hyaluronan binding characteristics of paired link modules are different from those of single link modules, and that the reported temporal co-expression of cartilage link protein and of neurocan in developing brain implicates the possibility of a cooperative function of these molecules.
Rauch
Uwe
U
Department of Experimental Pathology, Lund University, University Hospital, 22185 Lund, Sweden. uwe.rauch@pat.lu.se
Hirakawa
Satoshi
S
Oohashi
Toshitaka
T
Kappler
Joachim
J
Roos
Gunnel
G
D000409:Alanine / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002460:Cell Line; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism*; D017077:Culture Media, Conditioned; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000235:genetics / Q000378:metabolism*; D037181:Lectins, C-Type; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D058580:Neurocan; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D000099249:Proteoglycan Link Protein
D000409:Alanine; D000469:Alkaline Phosphatase; D015815:Cell Adhesion Molecules; D011508:Chondroitin Sulfate Proteoglycans; D017077:Culture Media, Conditioned; D016326:Extracellular Matrix Proteins; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid; D037181:Lectins, C-Type; D009419:Nerve Tissue Proteins; D058580:Neurocan; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; D000099249:Proteoglycan Link Protein; C072273:TNFAIP6 protein, human; C513057:Tnfaip6 protein, mouse; C513056:Tnfaip6 protein, rat; C076817:NCAN protein, human