4mgx
Crystal structure of human filamin C domains 4-5 and GPIB alpha cytoplasmic domain complex
Structural highlights
DiseaseFLNC_HUMAN Defects in FLNC are the cause of myopathy myofibrillar type 5 (MFM5) [MIM:609524. A neuromuscular disorder, usually with an adult onset, characterized by focal myofibrillar destruction and pathological cytoplasmic protein aggregations, and clinical features of a limb-girdle myopathy.[1] Defects in FLNC are the cause of myopathy distal type 4 (MPD4) [MIM:614065. MPD4 is a slowly progressive muscular disorder characterized by distal muscle weakness and atrophy affecting the upper and lower limbs. Onset occurs around the third to fourth decades of life, and patients remain ambulatory even after long disease duration. Muscle biopsy shows non-specific changes with no evidence of rods, necrosis, or inflammation.[2] FunctionFLNC_HUMAN Muscle-specific filamin, which plays a central role in muscle cells, probably by functioning as a large actin-cross-linking protein. May be involved in reorganizing the actin cytoskeleton in response to signaling events, and may also display structural functions at the Z lines in muscle cells. Critical for normal myogenesis and for maintaining the structural integrity of the muscle fibers. Publication Abstract from PubMedImmunoglobulin-like (Ig) domains are a widely expanded superfamily that acts as interaction motifs or as structural spacers in multi-domain proteins. Vertebrate filamins (FLNs), which are multifunctional actin binding proteins, consists of 24 Ig domains. We have recently discovered that in the C-terminal Rod 2 region of FLN, Ig domains interact with each other forming functional domain pairs, where the interaction with signaling and transmembrane proteins is mechanically regulated by weak actomyosin contraction forces. Here, we investigated if there are similar inter-domain interactions around domain 4 in the N-terminal Rod 1 region of FLN. Protein crystal structures revealed a new type of domain organization between domains 3, 4 and 5. In this module, domains 4 and 5 interact rather tightly whereas domain 3 has a partially flexible interface with domain 4. NMR peptide titration experiments showed that within the three domain module, domain 4 is capable for interaction with a peptide derived from platelet glycoprotein Ib. Crystal structure of FLN domains 4 and 5 in complex with the peptide revealed a typical beta sheet augmentation interaction observed for many FLN ligands. Domain 5 was found to stabilize domain 4, and this could provide a mechanism for the regulation of domain 4 interactions. A Novel Structural Unit in the N-Terminal Region of Filamins.,Sethi R, Seppala J, Tossavainen H, Ylilauri M, Ruskamo S, Pentikainen OT, Pentikainen U, Permi P, Ylanne J J Biol Chem. 2014 Jan 27. PMID:24469451[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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