title: Tandem repeats are involved in G1 domain inhibition of versican expression and secretion and the G3 domain enhances glycosaminoglycan modification and product secretion via the complement-binding protein-like motif.
abstract: The large aggregating chondroitin sulfate proteoglycans, including aggrecan, versican (PG-M), neurocan, and brevican, are characterized by N-terminal and C-terminal globular (or selectin-like) domains known as the G1 and G3 domains, respectively. For this study, we generated a series of expression constructs containing various combinations of chicken versican/PG-M domains and a leading peptide of link protein in order to examine the roles of the G1 and G3 domains in versican function. In transfection studies, we observed that the presence of the G1 domain was sufficient to inhibit product secretion, while the G3 domain enhanced this process. We also demonstrated that the G1 domain inhibited the attachment of glycosaminoglycan chains to the core proteins, while the G3 domain enhanced this process. Further studies revealed that inhibition of secretion by G1 was mediated by its two tandem repeats, while G3's promotion of glycosaminoglycan chain attachment was apparently dependent on G3's complement-binding protein (CBP)-like motif. The modulatory effects of these two molecular domains may contribute to versican's biological activities.
authors.affiliation: Sunnybrook & Women's College Health Sciences Centre and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M4N 3M5, Canada.
authors.forename: B L
authors.initials: BL
authors.lastname: Yang
authors.forename: L
authors.initials: L
authors.lastname: Cao
authors.forename: C
authors.initials: C
authors.lastname: Kiani
authors.forename: V
authors.initials: V
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: M E
authors.initials: ME
authors.lastname: Adams
authors.forename: B B
authors.initials: BB
authors.lastname: Yang
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002645:Chickens; D011508:Chondroitin Sulfate Proteoglycans / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D003165:Complement System Proteins / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism*; D037181:Lectins, C-Type; D016297:Mutagenesis, Site-Directed; D011509:Proteoglycans / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D015183:Restriction Mapping; D014162:Transfection; D053675:Versicans
chemical_list: D011508:Chondroitin Sulfate Proteoglycans; D006025:Glycosaminoglycans; D037181:Lectins, C-Type; D011509:Proteoglycans; D011994:Recombinant Proteins; D053675:Versicans; D003165:Complement System Proteins