Profilactin and the regulation of actin assembly and disassembly

• Actin filament assembly and disassembly are believed to be fundamental steps in the mechanism of cell motility in non-muscle cells. Profilactin is a complex between monomeric actin and a small protein, profilin, which inhibits the polymerization of the actin. It is assumed that profilactin is an unpolymerized storage form of actin in the cell and that profilin is of central importance to the regulation of actin physiology. Previously, biochemical characterization of calf spleen profilactin has been difficult because of a disturbing variability in the stability between different preparations of the complex.This thesis demonstrates that the major reason for the variation in the stability of profilactin was the presence of minute amounts of contaminating protein factors that affect actin polymerization, presumably by binding specifically to one of the ends of the actin polymer. Conditions for the removal of these contaminating factors have been worked out and for the isolation of intact homogeneous profilin and actin. It is shown that the properties of the reconstituted complex are essentially the same as those of the isolated 'native' complex. The effects of profilin on spleen actin assembly and disassembly have been studied and apparent dissociation constants have been determined for the spleen complex as well as for the heterologous complex formed between spleen profilin and actin isolated from rabbit skeletal muscle. Finally, it has been shown that the spleen proteins, both separately and as a complex, specifically interact with detergents and the hydrophobic probe DPH.

Ämnesord

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Zoology (hsv//eng)

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