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. Author manuscript; available in PMC: 2008 Apr 10.
Published in final edited form as: Cell. 2005 Dec 16;123(6):1147–1160. doi: 10.1016/j.cell.2005.08.047

Figure 4. ADMP Binds to Chordin and Tsg, and Cleavage by Xolloid-Related Metalloproteinase Restores Binding to ALK-2 Receptor.

Figure 4

Supernatants of cocultures of 293T cells were used for crosslinking experiments (A-C). Pure recombinant proteins from R&D Systems were used for receptor binding assays (D and E).

(A) ADMP protein forms a binary complex with Chordin (lane 5) or a ternary complex with Chordin and Tsg (lane 6), which can be inactivated by Xolloid-related (lanes 8 and 9).

(B) Tsg protein forms a molecular complex with ADMP and Chordin proteins (lanes 6 and 9).

(C) Crosslinked Xlr enzyme runs as a discrete oligomer (Xlrn).

(D) ADMP binds specifically to the type I receptor ALK2 (lane 4) but not to BMPR-1a (ALK-3), BMPR-1b (ALK-6), or BMPR-II (lanes 2, 3, and 5). Other panels show loading controls.

(E) ADMP binding to ALK-2 is partially blocked by Chordin (top panel, lane 3) and completely inhibited by Chordin and Tsg (lane 4). Importantly, cleavage of Chordin by the metalloproteinase Xlr restores ADMP binding to ALK-2 (lane 5).