The structure of the GPIb–filamin A complex

Abstract

Filamin A (FLNa), a dimeric actin crosslinking and scaffold protein with numerous intracellular binding partners, anchors the platelet adhesion glycoprotein (GP) Ib-IX-V receptor to actin cytoskeleton. We mapped the GPIb␣ binding site to a single domain of FLNa and resolved the structure of this domain and its interaction complex with the corresponding GPIb␣ cytoplasmic domain. This is the first atomic structure of this class of membrane glycoprotein-cytoskeleton connection. GPIb␣ binds in a groove formed between the C and D ␤ strands of FLNa domain 17. The interaction is strikingly similar to that between the ␤7 integrin tail and a different FLNa domain, potentially defining a conserved motif for FLNa binding. Nevertheless, the structures also reveal specificity of the interfaces, which explains different regulatory mechanisms. To verify the topology of GPIb-FLNa interaction we also purified the native complex from platelets and showed that GPIb interacts with the C-terminus of FLNa, which is in accordance with our biochemical and structural data. (Blood. 2006;107:1925-1932

Cystic Fibrosis Transmembrane Conductance Regulator Interacts with Multiple Immunoglobulin Domains of Filamin A

“…These interaction sequences are similar to those of FLNa-binding sites of all FLNa⅐partners for which atomic structures have been resolved (13)(14)(15)(16)21). In the in silico models (Fig.…”

“…4B. Val-11, Ser-13, and Leu-15 are identical to the corresponding amino acids of migfilin and glycoprotein Ib␣, which make hydrophobic contacts with FLNa (13,15). Phe-11 of rat and mouse CFTR is also identical to the corresponding amino acids of glycoprotein Ib␣, integrin ␤2, and FilGAP.…”

“…All characterized atomic structures of FLNa⅐partner complexes demonstrate that the partners bind in a groove formed between the C and D ␤ strands of FLNa Ig repeat (IgFLNa) and share a conserved motif for FLNa binding (13)(14)(15)(16). This motif is also found in CFTR .…”

Filamin A (FLNA) is required for cell–cell contact in vascular development and cardiac morphogenesis

“…Timed embryos (E10-E17) were fixed with 4% paraformaldehyde. Paraffin sections were stained with H&E. Frozen sections were analyzed with antibodies to PECAM, VE-Cadherin, NFATc1 (BD Pharmingen, San Diego, CA), Nidogen (Calbiochem, San Diego, CA), Doublecortin (29), ␣-smooth muscle actin (DCX and ␣SMA, respectively; Sigma, St. Louis, MO), phosphohistone H3 (Upstate, Billerica, MA), Flnb, and Flna (kindly provided by T. Stossel and J. Hartwig) (30). At least three mutant and three wild-type littermates were analyzed.…”

Dynamic force sensing of filamin revealed in single-molecule experiments

“…The major interaction sites within rod 2 are the odd-numbered domains, specifically domains 17, 19, and 21. The transmembrane interaction partners bind to these domains through a terminal peptide sequence that forms an additional β-strand extending the β-sheet structure of the domain (12,13) (Fig. 1B).…”