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Christina Sieber, Frank Plöger, Raphaela Schwappacher, Rolf Bechtold, Michael Hanke, Shinji Kawai, Yoshifumi Muraki, Mieko Katsuura, Michio Kimura, Maya Mouler Rechtman, Yoav I. Henis, Jens Pohl, Petra Knaus

Monomeric and dimeric GDF-5 show equal type I receptor binding and oligomerization capability and have the same biological activity

Keywords: BMP, BMP receptor, GDF-5, Smad signaling, TGF-? superfamily

Growth and differentiation factor 5 (GDF-5) is a homodimeric protein stabilized by a single disulfide bridge between cysteine 465 in the respective monomers, as well as by three intramolecular cysteine bridges within each subunit. A mature recombinant human GDF-5 variant with cysteine 465 replaced by alanine (rhGDF-5 C465A) was expressed in E. coli, purified to homogeneity, and chemically renatured. Biochemical analysis showed that this procedure eliminated the sole interchain disulfide bond. Surprisingly, the monomeric variant of rhGDF-5 is as potent in vitro as the dimeric form. This could be confirmed by alkaline phosphatase assays and Smad reporter gene activation. Furthermore, dimeric and monomeric rhGDF-5 show comparable binding to their specific type I receptor, BRIb. Studies on living cells showed that both the dimeric and monomeric rhGDF-5 induce homomeric BRIb and heteromeric BRIb/BRII oligomers. Our results suggest that rhGDF-5 C465A has the same biological activity as rhGDF-5 with respect to binding to, oligomerization of and signaling through the BMP receptor type Ib.

Biological Chemistry, Walter de Gruyter

Print ISSN: 1431-6730
Volume: 387, 04/2006
Pages: 451 - 460

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