Purification of the transforming growth factor-beta (TGF-beta) binding proteoglycan betaglycan.
We report the purification of betaglycan, a low-abundance membrane proteoglycan with high affinity for transforming growth factor-beta (TGF-beta). Betaglycan solubilized from rat embryo membrane preparations was purified to near-homogeneity by sequential chromatography through DEAE-Trisacryl, wheat germ lectin-Sepharose, and TGF-beta 1-agarose. Purified betaglycan has properties similar to betaglycan affinity-labeled in intact cells: it binds TGF-beta 1 and TGF-beta 2 with KD approximately 0.2 nM, contains heparan sulfate and chondroitin sulfate glycosaminoglycan (GAG) chains and N-linked glycans attached to a 110-kDa core protein, and can spontaneously associate with phosphatidylcholine liposomes. The betaglycan core obtained by enzymatic removal of the GAG chains has high affinity for TGF-beta and associates with artificial liposomes, indicating that the core protein binds TGF-beta and anchors to membranes independently of the GAG chains present on the native protein or of any ancillary protein.
Andres
J L
JL
Cell Biology and Genetics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Rönnstrand
L
L
Cheifetz
S
S
Massagué
J
J
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D006801:Humans; D008081:Liposomes / Q000378:metabolism; D008565:Membrane Proteins / Q000302:isolation & purification* / Q000378:metabolism; D011509:Proteoglycans / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D008081:Liposomes; D008565:Membrane Proteins; D011509:Proteoglycans; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; C071736:betaglycan