Actin filament-severing domain of plasma gelsolin
Gelsolin, a multifunctional actin-modulating protein, has two actin-binding sites which may interact cooperatively. Native gelsolin requires micromolar Ca/sup 2 +/ for optimal binding of actin to both sites, and for expression of its actin filament-servering function. Recent work has shown that an NH/sub 2/-terminal chymotryptic 17-kD fragment of human plasma gelsolin contains one of the actin-binding sites, and that this fragment binds to and severs actin filaments weakly irrespective of whether Ca/sup 2 +/ is present. The other binding site is Ca/sup 2 +/ sensitive, and is found in a chymotryptic peptide derived from the COOH-terminal two-thirds of plasma gelsolin; this fragment does not sever F-actin or accelerate the polymerization of actin. This paper documents that larger thermolysin-derived fragments encompassing the NH/sub 2/-terminal half of gelsolin sever actin filaments as effectively as native plasma gelsolin, although in a Ca/sup 2 +/-insensitive manner. This results indicates that the NH/sub 2/-terminal half of gelsolin is the actin-severing domain. The stringent Ca/sup 2 +/ requirement for actin severing found in intact gelsolin is not due to a direct effect of Ca/sup 2 +/ on the severing domain, but indirectly through an effect on domains in the COOH-terminal half of the molecule to allow exposure of both actin-binding sites.
- Research Organization:
- Massachusetts General Hospital, Boston, MA (United States)
- OSTI ID:
- 6550671
- Journal Information:
- J. Cell Biol.; (United States), Vol. 103:4
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques