Regulation of Microfilament Assembly

Schoepper, Beate; Weigt, Christiane; Wegner, Albrecht

doi:10.1007/978-3-642-75142-4_51

Cited by 1 publication

(4 citation statements)

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“…The rate constant for binding of gelsolin to polymeric actin, which was in best agreement with the experimental data if it was assumed to be fast (kfr = 3 X lo6 M-' s-I), differed significantly from the rate constant previously reported (1.5X104 M-l s-I. [28]). There are a number of conceivable reasons for this discrepancy.…”

Section: Discussionsupporting

confidence: 80%

“…It has been reported that the interaction of gelsolin with actin is regulated by the actin-bound nucleotide ATP or ADP [9]. In the previously reported experiment [28] filament subunits contained ADP, whereas in this study where actin filaments were fragmented immediately following their formation, subunits were likely to contain ATP. Perhaps, the type of the nucleotide is important for the ability of gelsolin to fragment actin filaments.…”

Section: Discussionmentioning

confidence: 44%

“…If the reported slow rate of binding of gelsolin to polymeric actin (kfr = 1.5X104 M-' s-', [28]) was taken into account, a calculation gave practically no acceleration of the assembly compared to the case where no fragmentation occurs (Figs 4 and 5). However, a considerably better fit of the calculated time-course to the measured rates of assembly was achieved when fragmentation was assumed to be fast, i. e. (Fig.…”

Section: Evaluation and Interpretation Of The Experimental Datamentioning

confidence: 96%

“…As fragmentation is expected to accelerate assembly of actin with gelsolin by production of additional pointed ends, the effect of fragmentation on the rate of assembly was considered. If the reported slow rate of binding of gelsolin to polymeric actin (kfr = 1.5X104 M-' s-', [28]) was taken into account, a calculation gave practically no acceleration of the assembly compared to the case where no fragmentation occurs (Figs 4 and 5). However, a considerably better fit of the calculated time-course to the measured rates of assembly was achieved when fragmentation was assumed to be fast, i. e. Curves calculated for higher rates of binding of gelsolin to filament subunits (kfr > 3 X 1 O6 M-' s-') revealed the same shape as those calculated for k, = 3X106 M-' s-'.…”

Section: Evaluation and Interpretation Of The Experimental Datamentioning

confidence: 96%

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Nucleation of Actin Polymerization by Gelsolin

Ditsch

Wegner

1994

European Journal of Biochemistry

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The time-course of assembly of actin with gelsolin was measured by the fluorescence increase of a fluorescent label covalently linked to actin. The actin concentrations ranged from values far below the critical concentration to values above the critical concentration of the pointed ends of actin filaments. If the concentration of actin was in the range of the critical monomer concentration (0.64 pM), the time-course of the concentration of actin assembled with gelsolin revealed a sigmoidal shape. At higher actin concentrations the time-course of association of actin with gelsolin approximated an exponential curve. The measured time-courses of assembly were quantitatively interpreted by kinetic rate equations. A poor fit was obtained if two actin molecules were assumed to bind to gelsolin to form a 1 : 2 gelsolin-actin complex and subsequently further actin molecules were assumed to polymerize onto the 1 : 2 gelsolin-actin complex toward the pointed end. A considerably better agreement between calculated and measured time-courses was achieved if additional creation of actin filaments by fast fragmentation of newly formed actin filaments by not yet consumed gelsolin was assumed to occur. This suggests that both polymerization of actin onto gelsolin and fragmentation of actin filaments contribute to formation of new actin filaments by gelsolin. Furthermore it could be demonstrated that below the critical monomer concentration appreciable amounts of actin are incorporated into gelsolin-actin oligomers.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 44%

Section: Evaluation and Interpretation Of The Experimental Datamentioning

confidence: 96%

Section: Evaluation and Interpretation Of The Experimental Datamentioning

confidence: 96%

See 2 more Smart Citations