title: Rabbit skeletal muscle actin behaves differently than Acanthamoeba actin when added to soluble extracts of Acanthamoeba castellanii.
abstract: Cold extracts of Acanthamoeba castellanii in polymerizing buffer contain 32 microM unpolymerized actin of which about 20% polymerizes (as measured by ultracentrifugation) when the extract is warmed to 22 degrees C. As quantified by the increase in fluorescence of pyrene-labeled actin, 16% of muscle G-actin and 46% of Acanthamoeba G-actin polymerized when 0.8 microM of each was added to warm extracts of Acanthamoeba. Added muscle F-actin (1.2 microM) rapidly and totally depolymerized and then partially repolymerized whereas 1.2 microM added Acanthamoeba F-actin was stable indefinitely. Furthermore, muscle actin subunits were completely removed from copolymers of muscle and Acanthamoeba F-actin while all the amoeba actin remained polymerized when the copolymers contained at least 50% amoeba actin. These results suggest that exogenous tracer actin may not be an accurate indicator of the dynamics of endogenous actin in extracts and cells.
authors.affiliation: Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
authors.forename: L S
authors.initials: LS
authors.lastname: Holliday
authors.forename: M R
authors.initials: MR
authors.lastname: Bubb
authors.forename: E D
authors.initials: ED
authors.lastname: Korn
mesh_terms: D000048:Acanthamoeba / Q000378:metabolism*; D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D007700:Kinetics; D046911:Macromolecular Substances; D009132:Muscles / Q000378:metabolism*; D011817:Rabbits / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014020:Tissue Extracts / Q000378:metabolism
chemical_list: D000199:Actins; D046911:Macromolecular Substances; D014020:Tissue Extracts