title: Identification of disulfide-linked transforming growth factor-beta 1-specific binding proteins in rat glomeruli.
abstract: We have identified two distinct classes of transforming growth factor-beta (TGF-beta)-binding proteins by affinity labeling rat glomeruli with 125I-TGF-beta 1 and 125I-TGF-beta 2. The first type consists of a group of proteins that bind TGF-beta 1 but do not bind TGF-beta 2. When 125I-TGF-beta 1 affinity-labeled glomeruli were separated under nonreducing conditions, four prominent bands with Mr values of 320,000, 260,000, 170,000, and 90,000 were observed. Following reduction, the 320,000 and 170,000 bands yielded only a 100,000 band, the 260,000 complex yielded bands of 200,000, 100,000, and 85,000, and the 90,000 band migrated with an Mr of 85,000. Binding of 125I-TGF-beta 1 to these proteins was unaffected by the addition of as much as a 1,000-fold excess of TGF-beta 2. The second type of glomerular TGF-beta-binding protein consists of Mr 160,000-200,000 and 280,000 proteins that bind both TGF-beta 1 and beta 2. Digestion of these affinity-labeled proteins with heparitinase and chondroitinase resulted in a decrease of approximately 40,000 in their apparent molecular weights. Glomerular TGF-beta 1-binding proteins are distinct from previously described TGF-beta-binding proteins in their specificity for TGF-beta 1 and their formation of disulfide-linked multimers. The TGF-beta 1/beta 2-binding proteins share some properties of the previously described type III TGF-beta receptor.
authors.affiliation: Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: K
authors.initials: K
authors.lastname: MacKay
authors.forename: A R
authors.initials: AR
authors.lastname: Robbins
authors.forename: M D
authors.initials: MD
authors.lastname: Bruce
authors.forename: D
authors.initials: D
authors.lastname: Danielpour
mesh_terms: D000345:Affinity Labels; D000818:Animals; D001667:Binding, Competitive; D002808:Chondroitin Lyases / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D007678:Kidney Glomerulus / Q000032:analysis*; D046911:Macromolecular Substances; D008297:Male; D008970:Molecular Weight; D017830:Octoxynol; D011092:Polyethylene Glycols; D011133:Polysaccharide-Lyases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000032:analysis* / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta; D015291:Transforming Growth Factors / Q000378:metabolism
chemical_list: D000345:Affinity Labels; D004220:Disulfides; D046911:Macromolecular Substances; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D011092:Polyethylene Glycols; D015291:Transforming Growth Factors; D017830:Octoxynol; C010615:Nonidet P-40; D002808:Chondroitin Lyases; D011133:Polysaccharide-Lyases; C021349:heparitinsulfate lyase