Domain analysis of supervillin, an F-actin bundling plasma membrane protein with functional nuclear localization signals
AuthorsWulfkuhle, J. D.
Donina, I. E.
Stark, N. H.
Pope, Robert K.
Pestonjamasp, Kersi N.
Niswonger, M. L.
Luna, Elizabeth J.
UMass Chan AffiliationsDepartment of Cell Biology
Green Fluorescent Proteins
Nuclear Localization Signals
Recombinant Fusion Proteins
Medicine and Health Sciences
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AbstractA growing number of actin-associated membrane proteins have been implicated in motile processes, adhesive interactions, and signal transduction to the cell nucleus. We report here that supervillin, an F-actin binding protein originally isolated from bovine neutrophil plasma membranes, contains functional nuclear targeting signals and localizes at or near vinculin-containing focal adhesion plaques in COS7-2 and CV1 cells. Overexpression of full-length supervillin in these cells disrupts the integrity of focal adhesion plaques and results in increased levels of F-actin and vinculin. Localization studies of chimeric proteins containing supervillin sequences fused with the enhanced green fluorescent protein indicate that: (1) the amino terminus promotes F-actin binding, targeting to focal adhesions, and limited nuclear localization; (2) the dominant nuclear targeting signal is in the center of the protein; and (3) the carboxy-terminal villin/gelsolin homology domain of supervillin does not, by itself, bind tightly to the actin cytoskeleton in vivo. Overexpression of chimeras containing both the amino-terminal F-actin binding site(s) and the dominant nuclear targeting signal results in the formation of large nuclear bundles containing F-actin, supervillin, and lamin. These results suggest that supervillin may contribute to cytoarchitecture in the nucleus, as well as at the plasma membrane.
SourceJ Cell Sci. 1999 Jul;112 ( Pt 13):2125-36. Link to article on publisher's website
Permanent Link to this Itemhttp://hdl.handle.net/20.500.14038/50775
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