'''Crystal structure of Bone Morphogenetic Protein-3 (BMP-3)'''
===Crystal structure of Bone Morphogenetic Protein-3 (BMP-3)===
==Overview==
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Bone morphogenetic proteins (BMPs) are extracellular messenger ligands involved in controlling a wide array of developmental and intercellular signaling processes. To initiate their specific intracellular signaling pathways, the ligands recognize and bind two structurally related serine/threonine kinase receptors, termed type I and type II, on the cell surface. Here, we present the crystal structures of BMP-3 and BMP-6, of which BMP-3 has remained poorly understood with respect to its receptor identity, affinity, and specificity. Using surface plasmon resonance (BIAcore) we show that BMP-3 binds Activin Receptor type II (ActRII) with Kd approximately 1.8 microM but ActRIIb with 30-fold higher affinity at Kd approximately 53 nM. This low affinity for ActRII may involve Ser-28 and Asp-33 of BMP-3, which are found only in BMP-3's type II receptor-binding interfaces. Point mutations of either residue to alanine results in up to 20-fold higher affinity to either receptor. We further demonstrate by Smad-based whole cell luciferase assays that the increased affinity of BMP-3S28A to ActRII enables the ligand's signaling ability to a level comparable to that of BMP-6. Focusing on BMP-3's preference for ActRIIb, we find that Lys-76 of ActRII and the structurally equivalent Glu-76 of ActRIIb are distinct between the two receptors. We demonstrate that ActRIIbE76K and ActRII bind BMP-3 with similar affinity, indicating BMP-3 receptor specificity is controlled by the interaction of Lys-30 of BMP-3 with Glu-76 of ActRIIb. These studies illustrate how a single amino acid can regulate the specificity of ligand-receptor binding and potentially alter biological signaling and function in vivo.
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==About this Structure==
==About this Structure==
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[[Category: Signaling protein]]
[[Category: Signaling protein]]
[[Category: Tgf-beta]]
[[Category: Tgf-beta]]
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Revision as of 21:21, 28 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
2QCQ is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
BMP-3 and BMP-6 structures illuminate the nature of binding specificity with receptors., Allendorph GP, Isaacs MJ, Kawakami Y, Belmonte JC, Choe S, Biochemistry. 2007 Oct 30;46(43):12238-47. Epub 2007 Oct 9. PMID:17924656
