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Full-Text Articles in Medicine and Health Sciences
Mutant Rac1b Expression In Dictyostelium: Effects On Morphology, Growth, Endocytosis, Development, And The Actin Cytoskeleton, S. Palmieri, Thomas Nebl, Robert Pope, D. Seastone, E. Lee, E. Hinchcliffe, Greenfield Sluder, D. Knecht, J. Cardelli, Elizabeth Luna
Mutant Rac1b Expression In Dictyostelium: Effects On Morphology, Growth, Endocytosis, Development, And The Actin Cytoskeleton, S. Palmieri, Thomas Nebl, Robert Pope, D. Seastone, E. Lee, E. Hinchcliffe, Greenfield Sluder, D. Knecht, J. Cardelli, Elizabeth Luna
Elizabeth J. Luna
Rac1 is a small G-protein in the Ras superfamily that has been implicated in the control of cell growth, adhesion, and the actin-based cytoskeleton. To investigate the role of Rac1 during motile processes, we have established Dictyostelium cell lines that conditionally overexpress epitope-tagged Dictyostelium discoideum wild-type Rac1B (DdRac1B) or a mutant DdRac1B protein. Expression of endogenous levels of myc- or GFP-tagged wild-type DdRac1B had minimal effect on cellular morphologies and behaviors. By contrast, expression of a constitutively active mutant (G12-->V or Q61-->L) or a dominant negative mutant (T17-->N) generated amoebae with characteristic cellular defects. The morphological appearance …
Direct Binding Of F-Actin To Ponticulin, An Integral Plasma Membrane Glycoprotein, C. Chia, Anne Hitt, Elizabeth Luna
Direct Binding Of F-Actin To Ponticulin, An Integral Plasma Membrane Glycoprotein, C. Chia, Anne Hitt, Elizabeth Luna
Elizabeth J. Luna
We have developed an 125I-labeled F-actin blot overlay assay for the identification of F-actin-binding proteins after transfer to nitrocellulose from SDS-polyacrylamide gels. Two major F-actin-binding proteins from Dictyostelium discoideum, a cytoplasmic 30 kDa protein and a 17 kDa integral membrane protein, and two minor membrane polypeptides of 19 kDa and 15 kDa were detected by this method. Using F-actin affinity and immunoaffinity chromatography, the 17 kDa polypeptide was identified as ponticulin, a previously described actin-binding glycoprotein from D. discoideum plasma membranes (Wuestehube, L.J., and Luna, E.J., [1987]: J. Cell Biol. 105:1741-1751). The binding of F-actin to ponticulin on blots is …
F-Actin And Myosin Ii Binding Domains In Supervillin, Yu Chen, Norio Takizawa, Jessica Crowley, Sang Oh, Cheryl Gatto, Taketoshi Kambara, Osamu Sato, Xiang-Dong Li, Mitsuo Ikebe, Elizabeth Luna
F-Actin And Myosin Ii Binding Domains In Supervillin, Yu Chen, Norio Takizawa, Jessica Crowley, Sang Oh, Cheryl Gatto, Taketoshi Kambara, Osamu Sato, Xiang-Dong Li, Mitsuo Ikebe, Elizabeth Luna
Elizabeth J. Luna
Detergent-resistant membranes contain signaling and integral membrane proteins that organize cholesterol-rich domains called lipid rafts. A subset of these detergent-resistant membranes (DRM-H) exhibits a higher buoyant density ( approximately 1.16 g/ml) because of association with membrane skeleton proteins, including actin, myosin II, myosin 1G, fodrin, and an actin- and membrane-binding protein called supervillin (Nebl, T., Pestonjamasp, K. N., Leszyk, J. D., Crowley, J. L., Oh, S. W., and Luna, E. J. (2002) J. Biol. Chem. 277, 43399-43409). To characterize interactions among DRM-H cytoskeletal proteins, we investigated the binding partners of the novel supervillin N terminus, specifically amino acids 1-830. We …
Membrane Cytoskeleton: Pip(2) Pulls The Strings, Thomas Nebl, Sang Oh, Elizabeth Luna
Membrane Cytoskeleton: Pip(2) Pulls The Strings, Thomas Nebl, Sang Oh, Elizabeth Luna
Elizabeth J. Luna
A recent application of optical tweezers has shown that plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP(2)) levels control adhesion of the membrane bilayer to the underlying cytoskeleton, by regulated direct binding of PIP(2) to cytoskeletal proteins and/or indirect effects on cytoskeleton structure.