scholarly journals The BPAG1 locus

2001 ◽  
Vol 154 (4) ◽  
pp. 691-698 ◽  
Author(s):  
Conrad L. Leung ◽  
Min Zheng ◽  
Susan M. Prater ◽  
Ronald K.H. Liem
Keyword(s):  
Coiled Coil ◽  
Binding Domain ◽  
Mutant Mice ◽  
Actin Binding ◽  
Spectrin Repeat ◽  
Binding Domains ◽  
Microtubule Binding Domain ◽  
Actin Binding Domain ◽  
Skin Fragility ◽  
Interaction Domains

Bullous pemphigoid antigen 1 (BPAG1) is a member of the plakin family with cytoskeletal linker properties. Mutations in BPAG1 cause sensory neuron degeneration and skin fragility in mice. We have analyzed the BPAG1 locus in detail and found that it encodes different interaction domains that are combined in tissue-specific manners. These domains include an actin-binding domain (ABD), a plakin domain, a coiled coil (CC) rod domain, two different potential intermediate filament–binding domains (IFBDs), a spectrin repeat (SR)-containing rod domain, and a microtubule-binding domain (MTBD). There are at least three major forms of BPAG1: BPAG1-e (302 kD), BPAG1-a (615 kD), and BPAG1-b (834 kD). BPAG1-e has been described previously and consists of the plakin domain, the CC rod domain, and the first IFBD. It is the primary epidermal BPAG1 isoform, and its absence that is the likely cause of skin fragility in mutant mice. BPAG1-a is the major isoform in the nervous system and a homologue of the microtubule actin cross-linking factor, MACF. BPAG1-a is composed of the ABD, the plakin domain, the SR-containing rod domain, and the MTBD. The absence of BPAG1-a is the likely cause of sensory neurodegeneration in mutant mice. BPAG1-b is highly expressed in muscles, and has extra exons encoding a second IFBD between the plakin and SR-containing rod domains of BPAG1-a.

scholarly journals A Coiled-Coil Domain of Melanophilin Is Essential for Myosin Va Recruitment and Melanosome Transport in Melanocytes

2006 ◽  
Vol 17 (11) ◽  
pp. 4720-4735 ◽  
Author(s):  
Alistair N. Hume ◽  
Abul K. Tarafder ◽  
José S. Ramalho ◽  
Elena V. Sviderskaya ◽  
Miguel C. Seabra
Keyword(s):  
Coiled Coil ◽  
Binding Domain ◽  
Actin Binding ◽  
Binding Studies ◽  
Null Cell ◽  
Coiled Coil Region ◽  
Actin Binding Domain ◽  
Transport Assay ◽  
Myosin Va

Melanophilin (Mlph) regulates retention of melanosomes at the peripheral actin cytoskeleton of melanocytes, a process essential for normal mammalian pigmentation. Mlph is proposed to be a modular protein binding the melanosome-associated protein Rab27a, Myosin Va (MyoVa), actin, and microtubule end-binding protein (EB1), via distinct N-terminal Rab27a-binding domain (R27BD), medial MyoVa-binding domain (MBD), and C-terminal actin-binding domain (ABD), respectively. We developed a novel melanosome transport assay using a Mlph-null cell line to study formation of the active Rab27a:Mlph:MyoVa complex. Recruitment of MyoVa to melanosomes correlated with rescue of melanosome transport and required intact R27BD together with MBD exon F–binding region (EFBD) and unexpectedly a potential coiled-coil forming sequence within ABD. In vitro binding studies indicate that the coiled-coil region enhances binding of MyoVa by Mlph MBD. Other regions of Mlph reported to interact with MyoVa globular tail, actin, or EB1 are not essential for melanosome transport rescue. The strict correlation between melanosomal MyoVa recruitment and rescue of melanosome distribution suggests that stable interaction with Mlph and MyoVa activation are nondissociable events. Our results highlight the importance of the coiled-coil region together with R27BD and EFBD regions of Mlph in the formation of the active melanosomal Rab27a-Mlph-MyoVa complex.

scholarly journals Microtubule Actin Cross-Linking Factor (Macf)

1999 ◽  
Vol 147 (6) ◽  
pp. 1275-1286 ◽  
Author(s):  
Conrad L. Leung ◽  
Dongming Sun ◽  
Min Zheng ◽  
David R. Knowles ◽  
Ronald K.H. Liem
Keyword(s):  
Calcium Binding ◽  
Coiled Coil ◽  
Specific Protein ◽  
Binding Domain ◽  
Full Length ◽  
Actin Binding ◽  
Cross Linking ◽  
Actin Binding Domain

We cloned and characterized a full-length cDNA of mouse actin cross-linking family 7 (mACF7) by sequential rapid amplification of cDNA ends–PCR. The completed mACF7 cDNA is 17 kb and codes for a 608-kD protein. The closest relative of mACF7 is the Drosophila protein Kakapo, which shares similar architecture with mACF7. mACF7 contains a putative actin-binding domain and a plakin-like domain that are highly homologous to dystonin (BPAG1-n) at its NH2 terminus. However, unlike dystonin, mACF7 does not contain a coiled–coil rod domain; instead, the rod domain of mACF7 is made up of 23 dystrophin-like spectrin repeats. At its COOH terminus, mACF7 contains two putative EF-hand calcium-binding motifs and a segment homologous to the growth arrest–specific protein, Gas2. In this paper, we demonstrate that the NH2-terminal actin-binding domain of mACF7 is functional both in vivo and in vitro. More importantly, we found that the COOH-terminal domain of mACF7 interacts with and stabilizes microtubules. In transfected cells full-length mACF7 can associate not only with actin but also with microtubules. Hence, we suggest a modified name: MACF (microtubule actin cross-linking factor). The properties of MACF are consistent with the observation that mutations in kakapo cause disorganization of microtubules in epidermal muscle attachment cells and some sensory neurons.

NUANCE, a giant protein connecting the nucleus and actin cytoskeleton

2002 ◽  
Vol 115 (15) ◽  
pp. 3207-3222 ◽  
Author(s):  
Yen-Yi Zhen ◽  
Thorsten Libotte ◽  
Martina Munck ◽  
Angelika A. Noegel ◽  
Elena Korenbaum
Keyword(s):  
Actin Cytoskeleton ◽  
Transmembrane Domain ◽  
Coiled Coil ◽  
Peripheral Blood Lymphocytes ◽  
Binding Domain ◽  
Actin Binding ◽  
Actin Binding Domain ◽  
Microfilament System

NUANCE (NUcleus and ActiN Connecting Element) was identified as a novel protein with an α-actinin-like actin-binding domain. A human 21.8 kb cDNA of NUANCE spreads over 373 kb on chromosome 14q22.1-q22.3. The cDNA sequence predicts a 796 kDa protein with an N-terminal actin-binding domain, a central coiled-coil rod domain and a predicted C-terminal transmembrane domain. High levels of NUANCE mRNA were detected in the kidney, liver,stomach, placenta, spleen, lymphatic nodes and peripheral blood lymphocytes. At the subcellular level NUANCE is present predominantly at the outer nuclear membrane and in the nucleoplasm. Domain analysis shows that the actin-binding domain binds to Factin in vitro and colocalizes with the actin cytoskeleton in vivo as a GFP-fusion protein. The C-terminal transmembrane domain is responsible for the targeting the nuclear envelope. Thus, NUANCE is the firstα-actinin-related protein that has the potential to link the microfilament system with the nucleus.

scholarly journals The C Terminus of Rotavirus VP4 Protein Contains an Actin Binding Domain Which Requires Cooperation with the Coiled-Coil Domain for Actin Remodeling

2018 ◽  
Vol 93 (1) ◽  
Author(s):  
Wilfried Condemine ◽  
Thibaut Eguether ◽  
Nathalie Couroussé ◽  
Catherine Etchebest ◽  
Agnes Gardet ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Coiled Coil ◽  
Binding Domain ◽  
Spike Protein ◽  
Actin Binding ◽  
Intestinal Cells ◽  
Actin Remodeling ◽  
Coiled Coil Domain ◽  
C Terminus ◽  
Actin Binding Domain

ABSTRACTThe interactions between viruses and actin cytoskeleton have been widely studied. We showed that rotaviruses remodel microfilaments in intestinal cells and demonstrated that this was due to the VP4 spike protein. Microfilaments mainly occur in the apical domain of infected polarized enterocytes and favor the polarized apical exit of viral progeny. The present work aims at the identification of molecular determinants of actin-VP4 interactions. We used various deletion mutants of VP4 that were transfected into Cos-7 cells and analyzed interactions by immunofluorescence confocal microscopy. It has been established that the C-terminal part of VP4 is embedded within viral particles when rotavirus assembles. The use of specific monoclonal antibodies demonstrated that VP4 is expressed in different forms in infected cells: classically as spike on the outer layer of virus particles, but also as free soluble protein in the cytosol. The C terminus of free VP4 was identified as interacting with actin microfilaments. The VP4 actin binding domain is unable to promote microfilament remodeling by itself; the coiled-coil domain is also required in this process. This actin-binding domain was shown to dominate a previously identified peroxisomal targeting signal, located in the three last amino acids of VP4. The newly identified actin-binding domain is highly conserved in rotavirus strains from species A, B, and C, suggesting that actin binding and remodeling is a general strategy for rotavirus exit. This provides a novel mechanism of protein-protein interactions, not involving cell signaling pathways, to facilitate rotavirus exit.IMPORTANCERotaviruses are causal agents of acute infantile viral diarrhea. In intestinal cells,in vitroas well asin vivo, virus assembly and exit do not imply cell lysis but rely on an active process in which the cytoskeleton plays a major role. We describe here a novel molecular mechanism by which the rotavirus spike protein VP4 drives actin remodeling. This relies on the fact that VP4 occurs in different forms. Besides its structural function within the virion, a large proportion of VP4 is expressed as free protein. Here, we show that free VP4 possesses a functional actin-binding domain. This domain, in coordination with a coiled-coil domain, promotes actin cytoskeleton remodeling, thereby providing the capacity to destabilize the cell membrane and allow efficient rotavirus exit.

scholarly journals The carboxyterminal EF domain of erythroid α-spectrin is necessary for optimal spectrin-actin binding

Blood ◽  
2010 ◽  
Vol 116 (14) ◽  
pp. 2600-2607 ◽  
Author(s):  
Catherine Korsgren ◽  
Samuel E. Lux
Keyword(s):  
Membrane Skeleton ◽  
Binding Domain ◽  
Actin Binding ◽  
Binary Interaction ◽  
Spectrin Repeat ◽  
Calcium Dependent ◽  
Actin Binding Domain ◽  
Ef Hands ◽  
Protein 4.1R ◽  
Skeletal Integrity

Abstract Spectrin and protein 4.1R crosslink F-actin, forming the membrane skeleton. Actin and 4.1R bind to one end of β-spectrin. The adjacent end of α-spectrin, called the EF domain, is calmodulin-like, with calcium-dependent and calcium-independent EF hands. The severely anemic sph1J/sph1J mouse has very fragile red cells and lacks the last 13 amino acids in the EF domain, implying that the domain is critical for skeletal integrity. To test this, we constructed a minispectrin heterodimer from the actin-binding domain, the EF domain, and 4 adjacent spectrin repeats in each chain. The minispectrin bound to F-actin in the presence of native human protein 4.1R. Formation of the spectrin-actin-4.1R complex was markedly attenuated when the minispectrin contained the shortened sph1J α-spectrin. The α-spectrin deletion did not interfere with spectrin heterodimer assembly or 4.1R binding but abolished the binary interaction between spectrin and F-actin. The data show that the α-spectrin EF domain greatly amplifies the function of the β-spectrin actin-binding domain (ABD) in forming the spectrin-actin-4.1R complex. A model, based on the structure of α-actinin, suggests that the EF domain modulates the function of the ABD and that the C-terminal EF hands (EF34) may bind to the linker that connects the ABD to the first spectrin repeat.

The interaction of plectin with actin: evidence for cross-linking of actin filaments by dimerization of the actin-binding domain of plectin

2001 ◽  
Vol 114 (11) ◽  
pp. 2065-2076 ◽  
Author(s):  
Lionel Fontao ◽  
Dirk Geerts ◽  
Ingrid Kuikman ◽  
Jan Koster ◽  
Duco Kramer ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Cell Types ◽  
Binding Domain ◽  
Actin Binding ◽  
Cross Linking ◽  
Binding Domains ◽  
Cell Matrix ◽  
Vitro Binding ◽  
Actin Binding Domain

Plectin is a major component of the cytoskeleton and is expressed in a wide variety of cell types. It plays an important role in the integrity of the cytoskeleton by cross-linking the three filamentous networks and stabilizing cell-matrix and cell-cell contacts. Sequence analysis showed that plectin contains a highly conserved actin-binding domain, consisting of a pair of calponin-like subdomains. Using yeast two-hybrid assays in combination with in vitro binding experiments, we demonstrate that the actin-binding domain of plectin is fully functional and preferentially binds to polymeric actin. The sequences required for actin binding were identified at the C-terminal end of the first calponin homology domain within the actin-binding domain of plectin. We found that the actin-binding domain of plectin is able to bundle actin filaments and we present evidence that this is mediated by the dimerization of this domain. In addition we also show that plectin and another member of the plakin family, dystonin, can heterodimerize by their actin-binding domains. We propose a new mechanism by which plectin and possibly also other actin-binding proteins can regulate the organization of the F-actin network in the cell.

scholarly journals αE-catenin actin-binding domain alters actin filament conformation and regulates binding of nucleation and disassembly factors

2013 ◽  
Vol 24 (23) ◽  
pp. 3710-3720 ◽  
Author(s):  
Scott D. Hansen ◽  
Adam V. Kwiatkowski ◽  
Chung-Yueh Ouyang ◽  
HongJun Liu ◽  
Sabine Pokutta ◽  
...  
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Binding Domain ◽  
Actin Binding ◽  
Filamentous Actin ◽  
Filament Structure ◽  
Actin Binding Domain ◽  
Filament Bundles ◽  
Underlying Mechanisms ◽  
Cell Cell

The actin-binding protein αE-catenin may contribute to transitions between cell migration and cell–cell adhesion that depend on remodeling the actin cytoskeleton, but the underlying mechanisms are unknown. We show that the αE-catenin actin-binding domain (ABD) binds cooperatively to individual actin filaments and that binding is accompanied by a conformational change in the actin protomer that affects filament structure. αE-catenin ABD binding limits barbed-end growth, especially in actin filament bundles. αE-catenin ABD inhibits actin filament branching by the Arp2/3 complex and severing by cofilin, both of which contact regions of the actin protomer that are structurally altered by αE-catenin ABD binding. In epithelial cells, there is little correlation between the distribution of αE-catenin and the Arp2/3 complex at developing cell–cell contacts. Our results indicate that αE-catenin binding to filamentous actin favors assembly of unbranched filament bundles that are protected from severing over more dynamic, branched filament arrays.

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