Membrane interactions with actin cytoskeleton
Worcester Foundation for Experimental Biology, Shrewsbury, MA 01545. Current Opinion in Cell Biology
(Impact Factor: 8.47).
03/1994; 6(1):120-30. DOI: 10.1016/0955-0674(94)90125-2
Recent advances have been made in our understanding of the direct binding of actin to integral membrane proteins. New information has been obtained about indirect actin-membrane associations through spectrin superfamily members and through proteins at the cytoplasmic surfaces of focal contacts and adherens junctions.
Available from: Caroline A Enns
- "The actin-and microtubule-based cytoskeletal systems are important for the structural integrity of the cell and play important roles in organelle position and movement (Langford, 1995; Lippincott-Schwartz et al., 1995). Actin is involved in adhesion of the cell to the substratum, maintenance of cell polarity and cell mobility (Hitt and Luna, 1994; Mays et al., 1994). Microtubules and their motor proteins maintain the spatial organization of various organelles and facilitate the delivery of transport intermediates between these organelles (Terasaki et al., 1986; Cooper et al., 1988; "
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ABSTRACT: Infection of human epithelial cells by Neisseria meningitidis (MC) and Neisseria gonorrhoeae (GC) increases the rate of degradation of LAMP1, a major integral membrane glycoprotein of late endosomes and lysosomes. Several lines of evidence indicate that the neisserial IgA1 protease is directly responsible for this LAMP1 degradation. LAMP1 contains an IgA1-like hinge region with potential cleavage sites for the neisserial type 1 and type 2 IgA1 proteases. Neisserial type 2 IgA1 protease cleaves purified LAMP1 in vitro. Unlike its wild-type isogenic parent, an iga− mutant of N. gonorrhoeae cannot affect LAMP1 turnover and its growth in epithelial cells is dramatically reduced. Thus, IgA1 protease cleavage of LAMP1 promotes intracellular survival of pathogenic Neisseria spp.
Available from: 126.96.36.199
- "Interactions between the plasma membrane and the underlying actin-based cytoskeleton are thought to be responsible for the control of many fundamental cellular processes, e.g., cell shape, maintenance of cellular integrity , and cell–cell and cell–substrate adhesion    . A key issue in cell biology is the identification and characterization of molecules that bind to F-actin and potentially participate in linking the cytoskeleton to the plasma membrane. "
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ABSTRACT: Interactions between cellular proteins and filamentous (F) actin are key to many cellular functions, e.g., cell motility, endocytosis, cell:cell adhesion, and cell:substrate adhesion. Previously, a functional assay using 125I-labeled F-actin to detect a subset of F-actin binding proteins by blot overlay was developed. We have modified this assay to use the fluorescent label, Alexa 488, in place of 125Iodine. The detection limit for Alexa 488-labeled actin using a Molecular Dynamics STORM 860 Fluorescence/PhosphorImager was as little as 100pg of labeled actin. The Alexa 488 F-actin assay detects the same proteins from Dictyostelium discoideum and with approximately the same sensitivity (approximately 10 microg/ml F-actin final concentration) as the analogous 125I-labeled F-actin blot overlay. The use of Alexa 488 F-actin for blot overlay assays requires no radioactive materials and generates no hazardous waste. Assays can be performed on the laboratory bench top and the blots imaged directly with a blue laser scanner, either wet or dry. In addition, the Alexa 488 fluorophore is highly resistant to photobleaching, does not decay, and may be stored frozen or lyophilized. Alexa 488 F-actin is a stable, cost-effective, nonhazardous probe used for rapid identification of a subset of F-actin binding proteins.
Available from: PubMed Central
- "These activated adhesion molecules are thought to recruit specific cytoplasmic proteins such as talin, vinculin, paxillin, ␣ -actinin, tensin, ZO-1, and various signaling molecules, which may nucleate and organize actin-based cytoskeletons underlying the cell adhesion domain (Yonemura et al., 1995; Burridge et al., 1997; Yamada and Geiger, 1997). The free surface domain is characterized by various types of cellular protrusions such as microvilli, filopodia, and lamellipodia which contain abundant actin filaments (Bretscher, 1991; Condeelis, 1993; Hitt and Luna, 1994; Mooseker and Cheney, 1995; Mitchison and Cramer, 1996). These cellular protrusions are known to be formed and destroyed dynamically in response to various signals (Chinkers et al., 1979; Stossel, 1993; Greenberg, 1995; Forte and Yao, 1996; Hallett, 1997; Tapon and Hall, 1997). "
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ABSTRACT: Ezrin/radixin/moesin (ERM) proteins have been thought to play a central role in the organization of cortical actin-based cytoskeletons including microvillar formation through cross-linking actin filaments and integral membrane proteins such as CD43, CD44, and ICAM-2. To examine the functions of these ERM-binding membrane proteins (ERMBMPs) in cortical morphogenesis, we overexpressed ERMBMPs (the extracellular domain of E-cadherin fused with the transmembrane/cytoplasmic domain of CD43, CD44, or ICAM-2) in various cultured cells. In cultured fibroblasts such as L and CV-1 cells, their overexpression significantly induced microvillar elongation, recruiting ERM proteins and actin filaments. When the ERM-binding domains were truncated from these molecules, their ability to induce microvillar elongation became undetectable. In contrast, in cultured epithelial cells such as MTD-1A and A431 cells, the overexpression of ERMBMPs did not elongate microvilli. However, in the presence of EGF, overexpression of ERMBMPs induced remarkable microvillar elongation in A431 cells. These results indicated that ERMBMPs function as organizing centers for cortical morphogenesis by organizing microvilli in collaboration with activated ERM proteins. Furthermore, immunodetection with a phosphorylated ERM-specific antibody and site-directed mutagenesis suggested that ERM proteins phosphorylated at their COOH-terminal threonine residue represent activated ERM proteins.
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