Biomaterial Database

Acanthamoeba profilin binding to fluorescein-labeled actins. 1987

L Plank, and B R Ware

The binding constants of Acanthamoeba profilin to fluorescein-labeled actin from Acanthamoeba and from rabbit skeletal muscle have been determined by measuring the reduction in the actin tracer diffusion coefficients, determined by fluorescence photobleaching recovery, as a function of added profilin concentration. Data were analyzed using a two-parameter nonlinear regression analysis to determine the profilin-actin dissociation constant Kd and the profilactin diffusion coefficient, DPA. For fluorescein-labeled Acanthamoeba actin, the least-squares estimates for Kd and DPA, along with approximate single standard deviation confidence intervals, are Kd = 48 (36, 63) microM and DPA = 6.72 (6.62, 6.81) X 10(-7) cm2s-1. For fluorescein-labeled skeletal muscle actin, the corresponding values are Kd = 147 (94, 225) microM and DPA = 6.7 (6.3, 7.0) X 10(-7) cm2s-1. These dissociation constants are the first to be determined from direct physical measurement; they are in agreement with values inferred from earlier studies on the effect of profilin on the assembly of actin that had been fluorescently labeled or otherwise modified at Cys 374. These results place important restrictions on the interpretation of experiments in which fluorescently labeled actin is used as a probe of living cytoplasm or cytoplasmic extracts that include profilin.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008840	Microfilament Proteins	Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.	Actin Binding Protein,Actin-Binding Protein,Actin-Binding Proteins,Microfilament Protein,Actin Binding Proteins,Binding Protein, Actin,Protein, Actin Binding,Protein, Actin-Binding,Protein, Microfilament,Proteins, Actin-Binding,Proteins, Microfilament
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011506	Proteins	Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.	Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D003285	Contractile Proteins	Proteins which participate in contractile processes. They include MUSCLE PROTEINS as well as those found in other cells and tissues. In the latter, these proteins participate in localized contractile events in the cytoplasm, in motile activity, and in cell aggregation phenomena.	Contractile Protein,Protein, Contractile,Proteins, Contractile
D005452	Fluoresceins	A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.	Tetraiodofluorescein
D000199	Actins	Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.	F-Actin,G-Actin,Actin,Isoactin,N-Actin,alpha-Actin,alpha-Isoactin,beta-Actin,gamma-Actin,F Actin,G Actin,N Actin,alpha Actin,alpha Isoactin,beta Actin,gamma Actin
D000656	Amoeba	A genus of ameboid protozoa. Characteristics include a vesicular nucleus and the formation of several PSEUDOPODIA, one of which is dominant at a given time. Reproduction occurs asexually by binary fission.	Ameba
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D051304	Profilins	A family of low molecular weight proteins that bind ACTIN and control actin polymerization. They are found in eukaryotes and are ubiquitously expressed.	Profilin,Profilin 1,Profilin 2,Profilin 3,Profilin 4,Profilin I,Profilin Proteins,Profilin-1,Profilin-2,Profilin-3,Profilin-4