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Control of profilin and actin expression in muscle and nonmuscle cells (1993)

Babcock, Gary ; Rubenstein, Peter A.

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 24 (1993), S. 179-188

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ISSN: 0886-1544

Keywords: protein synthesis ; northern analysis ; BC3H1 cells ; HepG-2 cells ; C2C12 cells ; profilactin ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Profilin is a small G-actin binding protein implicated in sequestering actin monomers in vivo. We have quantitated profilin and actin expression in human hepatoma HepG-2 cells and in two mouse myogenic cell lines, BC3H1 and C2C12, to determine whether the expression of profilin and the expression of nonmuscle isoactin or total actin are co-regulated. During differentiation of both muscle cell types, profilin and nonmuscle actin expression decrease in a coordinate manner as shown by measurements of steady state mRNA and newly synthesized protein. In human hepatoma HepG-2 cells, the twofold increase in actin synthesis observed after 24 hours of exposure to cytochalasin D did not result in an increase in profilin synthesis. Thus, profilin and actin expression are not coregulated in all cells. To determine if there is sufficient profilin to sequester a large portion of cellular G-actin, we measured total profilin and G-actin levels in the three cell types. In each case, profilin accounted for less than 10% of the total G-actin on a molar basis. Thus, profilin is not responsible for total G-actin sequestration in these cells. Finally, using poly-L-proline affinity chromatography, we showed that, in the cell types tested, less than 20% of the poly-L-proline purified profilin existed as a complex with G-actin. The profilin in these cells may be interacting with cellular components other than actin. © 1993 Wiley-Liss, Inc.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970240305

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Synthesis of mammalian profilin in Escherichia coli and Its characterization (1989)

Babcock, Gary ; Rubenstein, Peter A.

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 14 (1989), S. 230-236

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ISSN: 0886-1544

Keywords: profilactin ; actin ; cytoskeleton ; Trc promotor ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Profilin is a G-actin binding protein that may have a role in controlling the ratio of G/F actin within the cells To devise a way for obtaining large amounts of mammalian profilin in an active state, we transfected Escherichia coli with a plasmid containing a full-length rat spleen profilin cDNA adjacent to a promoter inducible by isopropyl thiogalactoside (IPTG). Upon induction, they synthesized a new protein of 15,000 MW constituting approximately 5% of the total cell protein. This protein bound to poly-L-proline Sepharose and could be eluted with 7 M urea, behavior similar to that exhibited by authentic profilin. The protein could be released from the bacteria in soluble form following sonication, and the profilin could then be purified to homogeneity following chromatography on Sephadex G-75 and DEAE A-50 Sephadex. The protein began with an unblocked Ala, indicating that the initiating formyl and methionine residues had been removed. The dissociation of the recombinant profilin from chicken skeletal muscle actin was characterized by a Kd of approximately 2 μM based on gel filtration analysis and actin polymerization assays. These results show that purified active mammalian profilin can be made conveniently in large quantities. This study also demonstrates the feasibility of using bacterially synthesized profilin in structure-function studies involving mutant profilins altered by site-directed mutagenesis.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970140209

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How does spatial resolution affect model performance? A case for ensemble approaches for marine benthic mesophotic communities (2019)

Joseph A. Turner, Russell C. Babcock, Gary A. Kendrick, Renae K. Hovey

Wiley

In: Journal of Biogeography

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Publication Date: 2019

Description: Abstract Aim To investigate how changing grid size can alter model predictions of the distribution of mesophotic taxa and how it affects different modelling methods. Location Ningaloo Marine Park, Western Australia. Taxon Benthic mesophotic taxa: corals, macroalgae and sponges. Methods We determined the distributions of the major benthic taxonomic groups: corals, macroalgae and sponges, using a number of modelling techniques and an ensemble using the ‘sdm’ R package. A range of grid sizes were used (10, 50, 100 and 250 m) to identify how model predictions were altered. Models were evaluated using the area under the curve of a receiver operator characteristic plot (AUC) and the true skill statistic (TSS) using a spatially independent dataset. Results Grid size had a large effect on model performance across the taxonomic groups. Model outputs were compared to null surfaces and 88.8% of models performed significantly better than null. Distribution of corals was best predicted using the finest grid size (10 m) regardless of modelling method, although a model ensemble produced the best results (AUC = 0.80, TSS = 0.52). Macroalgae and sponges were better predicted at coaster grids sizes (250 m). Again, ensembles performed well for both macroalgae (AUC = 0.83, TSS = 0.63) and sponges (AUC = 0.88, TSS = 0.66). Model ensembles maintained high accuracy across grid sizes and were consistently the best, or second‐best, performing method. Main conclusions This study has shown how grid size should be considered when producing distribution models. Identifying the most relevant grid size and being aware of the influence it may have will provide more accurate predictions of the distributions of taxa. Ensemble methods maintained good performance across scenarios and thus provide a useful tool for conservation and management especially where single modelling methods showed high levels of variability.

Print ISSN: 0305-0270

Electronic ISSN: 1365-2699

Topics: Biology , Geography

Published by Wiley

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