4b7l
Crystal Structure of Human Filamin B Actin Binding Domain with 1st Filamin Repeat
Structural highlights
DiseaseFLNB_HUMAN Note=Interaction with FLNA may compensate for dysfunctional FLNA homodimer in the periventricular nodular heterotopia (PVNH) disorder. Defects in FLNB are the cause of atelosteogenesis type 1 (AO1) [MIM:108720; also known as giant cell chondrodysplasia or spondylohumerofemoral hypoplasia. Atelosteogenesis are lethal short-limb skeletal dysplasias with vertebral abnormalities, disharmonious skeletal maturation, poorly modeled long bones and joint dislocations.[1] Defects in FLNB are the cause of atelosteogenesis type 3 (AO3) [MIM:108721. Atelosteogenesis are short-limb lethal skeletal dysplasias with vertebral abnormalities, disharmonious skeletal maturation, poorly modeled long bones and joint dislocations. In AO3 recurrent respiratory insufficiency and/or infections usually result in early death.[2] Defects in FLNB are the cause of boomerang dysplasia (BOOMD) [MIM:112310. This is a perinatal lethal osteochondrodysplasia characterized by absence or underossification of the limb bones and vertebre. Boomerang dysplasia is distinguished from atelosteogenesis on the basis of a more severe defect in mineralisation, with complete absence of ossification in some limb elements and vertebral segments.[3] Defects in FLNB are the cause of Larsen syndrome (LRS) [MIM:150250. An osteochondrodysplasia characterized by large-joint dislocations and characteristic craniofacial abnormalities. The cardinal features of the condition are dislocations of the hip, knee and elbow joints, with equinovarus or equinovalgus foot deformities. Spatula-shaped fingers, most marked in the thumb, are also present. Craniofacial anomalies include hypertelorism, prominence of the forehead, a depressed nasal bridge, and a flattened midface. Cleft palate and short stature are often associated features. Spinal anomalies include scoliosis and cervical kyphosis. Hearing loss is a well-recognized complication.[4] [5] Defects in FLNB are the cause of spondylocarpotarsal synostosis syndrome (SCT) [MIM:272460; also known as spondylocarpotarsal syndrome (SCT) or congenital synspondylism or vertebral fusion with carpal coalition or congenital scoliosis with unilateral unsegmented bar. The disorder is characterized by short stature and vertebral, carpal and tarsal fusions.[6] FunctionFLNB_HUMAN Connects cell membrane constituents to the actin cytoskeleton. May promote orthogonal branching of actin filaments and links actin filaments to membrane glycoproteins. Anchors various transmembrane proteins to the actin cytoskeleton. Interaction with FLNA may allow neuroblast migration from the ventricular zone into the cortical plate. Various interactions and localizations of isoforms affect myotube morphology and myogenesis. Isoform 6 accelerates muscle differentiation in vitro. Publication Abstract from PubMedThe filamin proteins cross-link F-actin and interact with protein partners to integrate both extra- and intra-cellular signaling events with the cytoskeleton and to provide mechanoprotection and sensing to cells. The filamins are large, flexible, multi-domain homodimers with the interactions between domains important for protein function. The crystal structure of the N-terminal region of filamin B, containing the actin binding domain (ABD) and the first filamin repeat (FR1) domain, reveals an extended two-domain conformation with no interaction between the ABD and FR1 other than the connecting linker region. The two FLNB347 structures in the crystallographic asymmetric unit exhibit differing relative domain orientations providing the first high-resolution structural characterisation of a filamin inter-domain conformational change. The structure reveals a new hinge in the linker region between ABD and FR1 that is ideally positioned to orient the ABD for actin binding and adds to the previously described hinge regions, hinge 1 (between repeats 15-16) and hinge 2 (repeats 23-24), providing an additional mechanism by which filamin can exhibit inter-domain flexibility. The extended structure, with the absence of interactions between the domains, implies that any conformational rearrangements required for actin binding by the ABD, as observed for homologous proteins, can freely occur without being influenced by FR1. The ABD retains its previously observed compact conformation. FR1 exhibits a filamin immunoglobulin-like domain fold with a closed C-D -strand groove, in contrast to filamin repeats that bind protein partners with this region of the domain surface. Crystal Structure Of The Filamin N-Terminal Region Reveals A Hinge Between The Actin Binding And First Repeat Domains.,Sawyer GM, Sutherland-Smith AJ J Mol Biol. 2012 Oct 1. pii: S0022-2836(12)00773-5. doi:, 10.1016/j.jmb.2012.09.016. PMID:23036857[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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