Tropomyosins Regulate the Impact of Actin Binding Proteins on Actin Filaments

Lindberg, Uno; Schutt, Clarence E.; Goldman, Robert D.; Nyåkern-Meazza, Maria; Hillberg, Louise; Rathje, Li Sophie Zhao; Grenklo, Staffan

doi:10.1007/978-0-387-85766-4_17

Cited by 12 publications

(22 citation statements)

References 57 publications

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“…Gel filtration chromatography was performed using a Superose 6 column [Grenklo et al, 2008]. Sample volume was 0.1 ml unless otherwise indicated, flow rate was 0.4 ml/min and fraction volume was 0.4 ml.…”

Section: Determination Of Molecular Weightmentioning

confidence: 99%

“…Analysis of cell extracts showed that these structures appears as actin-free multimers of TM [Grenklo et al, 2008]. Stimulation of cells with serum causes a rapid actin polymerization accompanied by a decrease of TM1 and TM4 multimers, respectively, which is followed by a pronounced increase in non-polymerized actin as well as the TM multimers.…”

mentioning

confidence: 97%

“…Stimulation of cells with serum causes a rapid actin polymerization accompanied by a decrease of TM1 and TM4 multimers, respectively, which is followed by a pronounced increase in non-polymerized actin as well as the TM multimers. Hence, it was suggested that the multimers serve as assembly intermediates, used in the formation of lamellipodia [Grenklo et al, 2008;Lindberg et al, 2008].It was demonstrated already in 1948, by Bailey that at low salt concentration TM can form polymers in the absence of actin filaments, and that these polymers are easily disassembled to dimers upon the addition of salt [Bailey, 1948]. The presence of TM multimers in cell extracts, appearing as actin-free distinct peaks, obtained by size chromatography, indicates alternate organisation forms of TM [Grenklo et al, 2008].…”

mentioning

confidence: 99%

“…Hence, it was suggested that the multimers serve as assembly intermediates, used in the formation of lamellipodia [Grenklo et al, 2008;Lindberg et al, 2008].…”

mentioning

confidence: 99%

“…Members of the formin family of proteins act as processive polymerases incorporating actin from P:A whilst remaining bound at the (þ)-end of the filaments [Carlier and Pantaloni, 2007;Renault et al, 2008]. Recently, the function of tropomyosin (TM), in the regulation of the actin filament (þ)-end has received increased attention [Hillberg et al, 2006;Wawro et al, 2007;Grenklo et al, 2008;Bach et al, 2009;Skau et al, 2009].Classically, TM participates in the calcium control of actomyosin force generation in the muscle, yet it is an abundant multi-isoform protein in non-muscle cells, see [Gunning et al, 2005. The isoforms are classified into two groups based on their polypeptide length; the low molecular weight (LMW; 247 amino acid residues and mw 28,000), and the high molecular weight (HMW; 284 residues and 32,000) isoforms.…”

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confidence: 99%

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Tropomyosin is a tetramer under physiological salt conditions

et al. 2010

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Tropomyosin (TM) is a coiled-coil dimer of alpha-helical peptides, which self associates in a head- to-tail fashion along actin polymers, conferring stability to the microfilaments and serving a regulatory function in acto-myosin driven force generation. While the major amount of TM is associated with filaments also in non-muscle cells, it was recently reported that there are isoform-specific pools of TM multimers (not associated with F-actin), which appear to be utilized during actin polymerization and reformed during depolymerization. To determine the size of these multimers, skeletal muscle TM was studied under different salt conditions using gel-filtration and sucrose gradient sedimentation, and compared with purified non-muscle TM 1 and 5, as well as with TM present in non-muscle cell extracts and skeletal muscle TM added to such extracts. Under physiological salt conditions TM appears as a single homogenous peak with the Stokes radius 8.2 nm and the molecular weight (mw) 130,000. The corresponding values for TM 5 are 7.7 nm and 104,000, respectively. This equals four peptides, implying that native TM is a tetramer in physiological salt. It is therefore concluded that the TM multimers are tetramers.

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Section: Determination Of Molecular Weightmentioning

confidence: 99%

mentioning

confidence: 97%

mentioning

confidence: 99%

“…Hence, it was suggested that the multimers serve as assembly intermediates, used in the formation of lamellipodia [Grenklo et al, 2008;Lindberg et al, 2008].…”

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confidence: 99%

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confidence: 99%

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Tropomyosin is a tetramer under physiological salt conditions

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Gelsolin: The tail of a molecular gymnast

et al. 2013

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Gelsolin superfamily members are Ca 21 -dependent, multidomain regulators of the actin cytoskeleton. Calcium binding activates gelsolin by inducing molecular gymnastics (large-scale conformational changes) that expose actin interaction surfaces by releasing a series of latches. A specialized tail latch has distinguished gelsolin within the superfamily. Active gelsolin exhibits actin filament severing and capping, and actin monomer sequestering activities. Here, we analyze a combination of sequence, structural, biophysical and biochemical data to assess whether the molecular plasticity, regulation and actinrelated properties of gelsolin are also present in other superfamily members. We conclude that all members of the superfamily will be able to transition between a compact conformation and a more open form, and that most of these open forms will interact with actin. Supervillin, which lacks the severing domain 1 and the F-actin binding-site on domain 2, is the clear exception. Eight calcium-binding sites are absolutely conserved in gelsolin, adseverin, advillin and villin, and compromised to increasing degrees in CapG, villin-like protein, supervillin and flightless I. Advillin, villin and supervillin each contain a potential tail latch, which is absent from CapG, adseverin and flightless I, and ambiguous in villin-like protein. Thus, calcium regulation will vary across the superfamily. Potential novel isoforms of the superfamily suggest complex regulation at the gene, transcript and protein levels. We review animal, clinical and cellular data that illuminate how the regulation of molecular flexibility in gelsolin-like proteins permits cells to exploit the force generated from actin polymerization to drive processes such as cell movement in health and disease. V C 2013 Wiley Periodicals, Inc.

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Cytoskeleton Dynamics and Binding Factors

Grintsevich

Reisler

2012

The Cytoskeleton

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Tropomyosins Regulate the Impact of Actin Binding Proteins on Actin Filaments

Cited by 12 publications

References 57 publications

Tropomyosin is a tetramer under physiological salt conditions

Tropomyosin is a tetramer under physiological salt conditions

Gelsolin: The tail of a molecular gymnast

Cytoskeleton Dynamics and Binding Factors

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