Kinetics of the cooperative association of actin to actin filament

Wegner, Albrecht; Engel, Juergen

doi:10.1016/0301-4622(75)80013-5

Cited by 235 publications

(208 citation statements)

References 25 publications

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“…Since both processes occur at the same rate following first-order kinetics, the ratedetermining step is assumed to be the dissociation step of one actin monomer from the polymer or the slowest step involved with this process. These results favour a depolymerisation mechanism in which spontaneous monomer dissociation occurs prior to complex formation with DNAase I, especially since the rate constant for the overall process is not faster than the monomer dissociation rate constant which has been measured previously [29].…”

Section: The Rate Of F-actin Depolymerisation By Dnaase Isupporting

confidence: 65%

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The Interaction of Bovine Pancreatic Deoxyribonuclease I and Skeletal Muscle Actin

Mannherz¹,

et al. 1980

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The rate of exchange of actin‐bound nucleotide is decreased by a factor of about 20 when actin is complexed with DNAase I without affecting the binding constant of calcium for actin. Binding constants of DNAase I to monomeric and filamentous actin were determined to be 5 × 108 M−1 and 1.2 × 104 M−1 respectively. The depolymerisation of F‐actin by DNAase I appears to be due to a shift in the G‐Fequilibrium of actin by DNAase I. Inhibition of the DNA‐degrading activity of DNAase I by G‐actin is of the partially competitive type.

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Section: The Rate Of F-actin Depolymerisation By Dnaase Isupporting

confidence: 65%

“…Due to the high rate of G-actin . DNAase I complex formation and the low rate of actin monomer dissociation from the polymer [29], the rate of de- polymerisation is assumed to follow first-order kinetics. This assumption was found to be correct as illustrated in Fig.…”

Section: The Rate Of F-actin Depolymerisation By Dnaase Imentioning

confidence: 99%

The Interaction of Bovine Pancreatic Deoxyribonuclease I and Skeletal Muscle Actin

Mannherz¹,

et al. 1980

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“…We preexchanged the bound metal before initiating the polymerization reaction so all reactions began with activated actin, A 1 . We assumed that nucleation consisted of a two-step addition of activated actin monomers: (24).…”

Section: Simulation Of the Time Course Of Polymerizationmentioning

confidence: 99%

“…The rate of elongation was assumed to be equal to the product of the concentration of actin, the concentration of actin filaments of any length (N), and the elongation rate constant (24). The rate of shortening was given by the product of N and rate constant k 6 .…”

Section: Simulation Of the Time Course Of Polymerizationmentioning

confidence: 99%

“…Fesselin reduced the duration of the lag of polymerization and eliminated it completely at sufficiently high concentrations. The lag phase in the polymerization results from the ratelimiting formation of nuclei consisting of three or four actin monomers (24,27,28,40).Fesselin had a modest effect on the rate of elongation of actin filaments. Fesselin had no effect on the critical concentration defined as the ratio of the sum of the rate constants for shortening at both ends (k 6 ) to the sum of the rate constants for elongation at the pointed and barbed ends (k 5 ) (27,28).…”

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Fesselin, a Synaptopodin-like Protein, Stimulates Actin Nucleation and Polymerization

Beall

Chalovich

2001

Biochemistry

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Fesselin is a proline-rich actin binding protein that has recently been isolated from smooth muscle [Leinweber, B. D., Fredricksen, R. S., Hoffman, D. R., and Chalovich, J. M. (1999) J. Muscle Res. Cell Motil. 20,[539][540][541][542][543][544][545]. Fesselin is similar to synaptopodin [Mundel, P., Heid, H. W., Mundel, T. M., Krüger, M., Reiser, J., and Kriz, W. (1997) J. Cell Biol. 139, 193-204] in terms of its size, isoelectric point, and sequence although synaptopodin is not present in smooth muscle. The function of fesselin is unknown. Evidence is presented here that fesselin accelerates the polymerization of actin. Fesselin was effective on actin isolated from either smooth or skeletal muscle at low ionic strength and in the presence of 100 mM KCl. At low ionic strength, fesselin decreased the time for 50% polymerization to about 1% of that in the absence of fesselin. The lag phase characteristic of the slow nucleation process of polymerization was eliminated as the fesselin concentration was increased from very low levels. Fesselin did not alter the critical concentration for actin but did increase the rate of elongation by ≈3-fold. The increase in elongation rate constant is insufficient to account for the total increase in polymerization rate. It is likely that fesselin stabilizes the formation of actin nuclei. Time courses of actin polymerization at varied fesselin concentrations and varied actin concentrations were simulated by increasing the rate of nucleation and both the forward and reverse rate constants for elongation.Fesselin is an actin binding protein that has recently been isolated from turkey gizzard muscle (1). Fesselin is noteworthy because of its potent ability to bundle actin and because of its similarity to synaptopodin, a protein found in telencephalic dendrites and renal podocytes but not in smooth muscle (2). Fesselin has in common with synaptopodin a similar pI (9.3), a similar mobility on SDS gels (103 and 79 kDa for fesselin and 110 kDa for synaptopodin), a high proline content, and regions of sequence homology. Antibodies directed against synaptopodin decorate actin filaments in cells forming a punctate pattern (2); this pattern is lost following depolymerization of actin with cytochalasin B. Preliminary studies with fesselin also indicate that fesselin co-localizes with α-actinin on actin filaments (3). The functions of fesselin and synaptopodin are unknown.The effect of fesselin on actin polymerization was examined because of its ability to bind to and bundle actin filaments and its high isoelectric point. The isoelectric point was a consideration because cationic substances tend to polymerize actin (4,5). Actin binding and polymerizing proteins are often basic (6), and charge neutralization may be a factor in the function of these proteins (5).The present study provides evidence that fesselin increases the rate of actin polymerization. This was seen by increases in the apparent rates of increase of both pyrene fluorescence and † Funded by NIH Grant AR35216 and a Facult...

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Irreversibly sickled cell β-actin: Defective filament formation

Shartava¹,

Korn²,

Shah³

et al. 1997

Am. J. Hematol.

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It has been demonstrated that cysteine modification in irreversibly sickled cell beta-actin slows down the remodeling of membrane skeletons [Shartava et al.: J Cell Biol 128:805-812, 1995]. This slow remodeling can be due to alterations in spectrin-actin binding and/or actin-actin interactions in irreversibly sickled cell (ISC) membrane skeletons. In these studies we demonstrate that ISC actin binds spectrin normally. However, ISC beta-actin polymerizes and depolymerizes more slowly than control beta-actin, and forms unusual aggregates when placed under polymerizing conditions. Electron microscopic analysis of actin polymers indicated that ISC actin generates a large amount of aggregates which we conclude are due to the structural modification caused by the disulfide bridge between cysteine284 and cysteine373 in beta-actin.

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Kinetics of the cooperative association of actin to actin filament

Cited by 235 publications

References 25 publications

The Interaction of Bovine Pancreatic Deoxyribonuclease I and Skeletal Muscle Actin

The Interaction of Bovine Pancreatic Deoxyribonuclease I and Skeletal Muscle Actin

Fesselin, a Synaptopodin-like Protein, Stimulates Actin Nucleation and Polymerization

Irreversibly sickled cell β-actin: Defective filament formation

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