Isolation of an abundant 50,000-dalton actin filament bundling protein from Dictyostelium amoebae.
A monomeric actin bundling protein with a native molecular weight of approximately 50,000 (ABP-50) has been isolated from amoebae of Dictyostelium discoideum. ABP-50 cross-links F-actin to form tightly packed bundles, some of which are highly ordered. It exhibits a Kd of 2.1 microM and a molar ratio to actin of 1:1 in bundles. Calcium and ATP at physiological concentrations have no effect on these activities. ABP-50 is immunologically unrelated to 30-kDa protein, a previously described bundling protein from Dictyostelium. Immunofluorescence with affinity-purified polyclonal antibodies indicates that ABP-50 is localized in regions of the amoeboid cell cortex containing actin bundles. The molar ratio of ABP-50 to actin is approximately 1:5 in vivo. Therefore, the abundance of ABP-50 suggests that it may be responsible for the majority of the bundling activity in these cells.
Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461.
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Demma
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Warren
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Hock
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Dharmawardhane
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Condeelis
D000199:Actins / Q000378:metabolism / Q000648:ultrastructure; D000906:Antibodies; D002458:Cell Fractionation; D002846:Chromatography, Affinity; D004023:Dictyostelium / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D008840:Microfilament Proteins / Q000302:isolation & purification* / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D008970:Molecular Weight
D000199:Actins; D000906:Antibodies; D008840:Microfilament Proteins; C052523:actin filament bundling proteins