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Biochemical evidence for interaction between smoothelin and filamentous actin

Niessen, Petra
Rensen, Sander
Van Eys, Guillaume
Published in Experimental cell research. 2004, vol. 292, no. 1, p. 170-178
Abstract The two major isoforms of smoothelin (A and B) contain a calponin homology (CH) domain, colocalize with alpha-smooth muscle actin (alpha-SMA) in stress fibers and are only expressed in contractile smooth muscle cells (SMCs). Based on these findings, we hypothesized that smoothelins are involved in smooth muscle cell contraction, presumably via interaction with actin. The interaction between smoothelins and three different actin isoforms (alpha- and gamma-smooth muscle and alpha-skeletal actin [alpha-SKA]) was investigated using several in vitro assays. Smoothelin-B co-immunoprecipitated with alpha-smooth muscle actin from pig aorta extracts. In rat embryonic fibroblasts, transfected smoothelins-A and -B associated with stress fibers. In vitro dot blot assays, in which immobilized actin was overlaid with radio-labeled smoothelin, showed binding of smoothelin-A to actin filaments, but not to monomeric G-actin. A truncated smoothelin, containing the calponin homology domain, associated with stress fibers when transfected and bound to actin filaments in overlay, but to a lesser extent. ELISA results showed that the binding of smoothelin to actin has no significant isoform specificity. Our results indicate an interaction between smoothelin and actin filaments. Moreover, the calponin homology domain and its surrounding sequences appear to be sufficient to accomplish this interaction, although the presence of other domains is apparently necessary to facilitate and/or strengthen the binding to actin.
Keywords Actins/ metabolismAnimalsAorta/chemistryCalcium-Binding Proteins/metabolismCell LineCytoskeletal Proteins/chemistry/genetics/ metabolismEnzyme-Linked Immunosorbent AssayEscherichia coli/geneticsFibroblasts/cytology/ metabolismGlutathione Transferase/metabolismMicrofilament ProteinsMuscle ProteinsPrecipitin TestsProtein Isoforms/chemistry/genetics/ metabolismProtein Structure, TertiaryRats/ embryologyRecombinant Fusion Proteins/metabolismStress Fibers/metabolismSwineTransfection
PMID: 14720516
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NIESSEN, Petra et al. Biochemical evidence for interaction between smoothelin and filamentous actin. In: Experimental cell research, 2004, vol. 292, n° 1, p. 170-178. doi: 10.1016/j.yexcr.2003.09.005 https://archive-ouverte.unige.ch/unige:11488

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Deposited on : 2010-08-27

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