Phalloidin Binding and Rheological Differences among Actin Isoforms

Actin is a highly conserved protein in eukaryotes, yet different isoforms of this protein can be found within the same cell. To begin to explore whether isoactin sequence diversity leads to functional differences in actin filaments, we have examined the phalloidin binding kinetics and the bulk rheol...

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Published inBiochemistry (Easton) Vol. 35; no. 45; pp. 14062 - 14069
Main Authors Allen, P. G, Shuster, C. B, Käs, J, Chaponnier, C, Janmey, P. A, Herman, I. M
Format Journal Article
LanguageEnglish
Published United States American Chemical Society 12.11.1996
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Summary:Actin is a highly conserved protein in eukaryotes, yet different isoforms of this protein can be found within the same cell. To begin to explore whether isoactin sequence diversity leads to functional differences in actin filaments, we have examined the phalloidin binding kinetics and the bulk rheologic properties of purified actin isoforms from a variety of eukaryotic sources. We observe differences in the phalloidin association kinetics between muscle α- and cytoplasmic actins. Phalloidin dissociates from all mammalian actin isoforms tested at the same slow rate, while dissociation from yeast actin is 1 order of magnitude more rapid. The actin isoforms form viscoelastic gels to varying degrees with skeletal muscle α-actin gels being the most elastic, smooth muscle α- and γ-actins being less elastic, and β-actin not forming elastic structures under our experimental conditions. The sequence variation among isoforms is discussed in light of these biophysical and biochemical differences.
Bibliography:Abstract published in Advance ACS Abstracts, October 15, 1996.
Supported by a Grant in Aid from the American Heart Association, Massachusetts Affiliate, to P.G.A., by CF Foundation Research Grant G957 to P.A.J., and by Swiss National Science Foundation Grant 31.43582.95 to C.C.
istex:3E0009B32417BBB90529C723B3642DEB8159BE43
ark:/67375/TPS-6TWZP59G-2
ISSN:0006-2960
1520-4995
DOI:10.1021/bi961326g