The C-type lectin domains of lecticans, a family of aggregating chondroitin sulfate proteoglycans, bind tenascin-R by protein-protein interactions independent of carbohydrate moiety.
The lecticans are a family of chondroitin sulfate proteoglycans including aggrecan, versican, neurocan, and brevican. The C-terminal globular domains of lecticans are structurally related to selectins, consisting of a C-type lectin domain flanked by epidermal growth factor and complement regulatory protein domains. The C-type lectin domain of versican has been shown to bind tenascin-R, an extracellular matrix protein specifically expressed in the nervous system, and the interaction was presumed to be mediated by a carbohydrate-protein interaction. In this paper, we show that the C-type lectin domain of brevican, another lectican that is specifically expressed in the nervous system, also binds tenascin-R. Surprisingly, this interaction is mediated by a protein-protein interaction through the fibronectin type III domains 3-5 of tenascin-R, independent of any carbohydrates or sulfated amino acids. The lectin domains of versican and other lecticans also bind the same domain of tenascin-R by protein-protein interactions. Surface plasmon resonance analysis revealed that brevican lectin has at least a 10-fold higher affinity than the other lectican lectins. Tenascin-R is coprecipitated with brevican from adult rat brain extracts, suggesting that tenascin-R and brevican form complexes in vivo. These results demonstrate that the C-type lectin domain can interact with fibronectin type III domains through protein-protein interactions, and suggest that brevican is a physiological tenascin-R ligand in the adult brain.
Aspberg
A
A
The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
Miura
R
R
Bourdoulous
S
S
Shimonaka
M
M
Heinegârd
D
D
Schachner
M
M
Ruoslahti
E
E
Yamaguchi
Y
Y
D000818:Animals; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D002460:Cell Line; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D037102:Lectins / Q000737:chemistry*; D008024:Ligands; D011485:Protein Binding; D051381:Rats; D019063:Tenascin / Q000378:metabolism*
D002241:Carbohydrates; D011508:Chondroitin Sulfate Proteoglycans; D037102:Lectins; D008024:Ligands; D019063:Tenascin; C074638:tenascin R