Membrane skeleton: Difference between revisions
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Supervillin ([[SVIL]]) is tightly associated with both actin filaments and plasma membranes, suggesting a role as a high-affinity link between the actin cytoskeleton and the membrane. Its function may include recruitment of actin and other cytoskeletal proteins into specialized structures at the plasma membrane.<ref name=Pestonjamasp>{{cite journal | author=Pestonjamasp KN, Pope RK, Wulfkuhle JD, Luna EJ |title=Supervillin (p205): A novel membrane-associated, F-actin-binding protein in the villin/gelsolin superfamily. |journal=J Cell Biol. |volume=139 |issue= 5 |pages= 1255-69 |year= 1997 |pmid= 9382871 |doi= }}</ref><ref name=Oh>{{cite journal | author=Oh SW, Pope RK, Smith KP, ''et al.'' |title=Archvillin, a muscle-specific isoform of supervillin, is an early expressed component of the costameric membrane skeleton. |journal=J Cell Sci. |volume=116 |issue= Pt 11 |pages= 2261-75 |year= 2004 |pmid= 12711699 |doi= 10.1242/jcs.00422 }}</ref> | Supervillin ([[SVIL]]) is tightly associated with both actin filaments and plasma membranes, suggesting a role as a high-affinity link between the actin cytoskeleton and the membrane. Its function may include recruitment of actin and other cytoskeletal proteins into specialized structures at the plasma membrane.<ref name=Pestonjamasp>{{cite journal | author=Pestonjamasp KN, Pope RK, Wulfkuhle JD, Luna EJ |title=Supervillin (p205): A novel membrane-associated, F-actin-binding protein in the villin/gelsolin superfamily. |journal=J Cell Biol. |volume=139 |issue= 5 |pages= 1255-69 |year= 1997 |pmid= 9382871 |doi= }}</ref><ref name=Oh>{{cite journal | author=Oh SW, Pope RK, Smith KP, ''et al.'' |title=Archvillin, a muscle-specific isoform of supervillin, is an early expressed component of the costameric membrane skeleton. |journal=J Cell Sci. |volume=116 |issue= Pt 11 |pages= 2261-75 |year= 2004 |pmid= 12711699 |doi= 10.1242/jcs.00422 }}</ref> | ||
=[[Meiosis#Synchronous processes|Meiosis]]= | |||
Aster microtubules radiate from the centrosome into the cytoplasm or contact components of the membrane skeleton. | |||
=References= | =References= | ||
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Editor-In-Chief: Henry A. Hoff
Overview
The interface formed by the interactions between the cell membrane and the cytoskeleton, often called the membrane skeleton (MSK), performs a variety of functions for the cell. The MSK works as a part of the plasma membrane as well as a part of the cytoskeleton. It is a scaffolding for membrane proteins to anchor to, and for forming organelles which extend from the cell. When high dynamicism is needed for drastic change in cell shape, effort is focussed at the MSK. It is involved in the localization of transmembrane proteins at specific sites in the cell membrane and in endocytosis and exocytosis in various cell types. The MSK provides the plasma membrane with the mechanical strength and resilience to withstand the stress and shear forces from the outside environment, while contributing stretch and shear elasticity. Signals originating at the cell membrane are transmitted to the cytoskeleton. It even participates in meiosis.
Introduction
An interface formed by the interactions[1] between the plasma membrane and the cytoskeleton is often referred to as the ‘’’plasma membrane skeleton’’’.[2] Co-ordinating the rearrangements of the actin portion of the cytoskeleton depends on its tight connection to the plasma membrane.[2] There is a physical linkage of the cell membrane to the underlying MSK. The MSK may cover the entire cytoplasmic suface and is closely linked to clathrin-coated pits and caveolae.[3] The MSK may differ from the bulk cytoskeleton in terms of its structure and protein composition, for its interactions with the plasma membrane in general and with specific molecules in the plasma membrane, and because it plays important roles in a variety of membrane functions.
Partitioning of the cell membrane
The MSK is involved in the localization of transmembrane proteins at specific sites in the cell membrane.[3] A part of the MSK, directly and closely associated with the cytoplasmic surface of the plasma membrane, induces partitioning of the cell membrane with regard to the translational diffusion of membrane molecules, based on high speed single-particle tracking data on membrane proteins and lipids.[3] In the short-time regime, these membrane molecules are temporarily confined within the compartments delimited by the MSK mesh, and, in the long-time regime, they undergo macroscopic diffusion by hopping between these compartments (MSK fence model). In the fence model, as a result of the collision of the cytoplasmic domains of transmembrane proteins with the MSK, transmembrane proteins are temporarily confined in the MSK mesh.[3]
Lipid molecules also undergo hop diffusion.
Specific proteins that link the membrane and actin filaments at their barbed ends, such as gelsolin and villin, and at their sides, such as ponticulin and ezrin/radixin/moesin family proteins, occur at the interface of the MSK. In addition to actin and actin-associated proteins, some other proteins may contribute to forming the MSK and membrane corrals, e.g., septins and agorin.[3]
Receptor-mediated endocytosis
Receptor-mediated endocytosis depends on the interaction between dynamin, a GTPase, and PtdIns(4,5)P2 (PIP2).[2] The local adhesion between the plasma membrane and the actin cytoskeleton, determined by measuring the energy necessary to separate the plasma membrane from the underlying actin cytoskeleton, can be influenced by changes in the levels of PIP2 at the plasma membrane.[2] PIP2 localizes to actin-rich structures in highly dynamic regions of the cell membrane and its retention and clustering at the plasma membrane influences actin cytoskeleton dynamics.[2] High concentrations of PIP2 are accompanied by extensive actin polymerisation.[2]
PIP2 directly binds to profilin, an actin-monomer-sequestering protein, and this binding induces the release of G-actin from the profilin-actin complex.[2] PIP2 is a regulatory mechanism on profilin, regulating the association of profilin with actin.[4] Profilin can regulate polymerization by binding to the ends of the actin filaments rather than the monomers.[5]
Spectrin-actin network
MSK provides the plasma membrane with the mechanical strength and resilience to withstand the stress and shear forces from the outside environment, which is well established in the thick cortical actin layers in immune cells and in the spectrin–actin network in red blood cells.[3] The erythrocyte membrane skeleton, which is localized exclusively on the cytoplasmic surface of the plasma membrane, is a network of proteins, mainly spectrins, actins, and band 4.1[6].
Signaling
Signals originating at the plasma membrane may be transmitted by PIP2 to the underlying actin cytoskeleton.[2] Signaling intermediates including focal adhesion molecules as vinculin and members of the ERM and WASP families of proteins interact with PIP2.[2]
Physical linkage
Physical linkage of the plasma membrane to the underlying membrane skeleton is via binding with ankyrin and protein 4.2. Binding also occurs with band 3 which appears to be to prevent membrane surface loss.
Supervillin (SVIL) is tightly associated with both actin filaments and plasma membranes, suggesting a role as a high-affinity link between the actin cytoskeleton and the membrane. Its function may include recruitment of actin and other cytoskeletal proteins into specialized structures at the plasma membrane.[7][8]
Meiosis
Aster microtubules radiate from the centrosome into the cytoplasm or contact components of the membrane skeleton.
References
- ↑ Doherty GJ, McMahon HT (2008). "Mediation, Modulation and Consequences of Membrane-Cytoskeleton Interactions". Annual Review of Biophysics. 37: 65–95. doi:10.1146/annurev.biophys.37.032807.125912. PMID 18573073.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Sechi AS, Wehland J (2000). "The actin cytoskeleton and plasma membrane connection: PtdIns(4,5)P2 influences cytoskeletal protein activity at the plasma membrane". J Cell Sci. 113 (Pt 21): 3685–95. PMID 11034897. Unknown parameter
|month=ignored (help) - ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Morone N, Fujiwara T, Murase K, Kasai RS, Ike H, Yuasa S, Usukura J, Kusumi A (2006). "Three-dimensional reconstruction of the membrane skeleton at the plasma membrane interface by electron tomography". J Cell Biol. 174 (6): 851–62. doi:10.1083/jcb.200606007. PMID 16954349. Unknown parameter
|month=ignored (help) - ↑ Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P (2002). The Molecular Biology of Cell. Garland Science Textbooks.
- ↑ Witke W, Podtelejnikov A, Di Nardo A, Sutherland J, Gurniak C, Dotti C, Mann M (1998). "In Mouse Brain Profilin I and Profilin II Associate With Regulators of the Endocytic Pathway and Actin Assembly". EMBO J. 17 (4): 967–76. PMID 9463375.
- ↑ Conboy J, Kan YW, Shohet SB, Mohandas N (1987). "Molecular cloning of protein 4.1, a major structural element of the human erythrocyte membrane skeleton". Proc Natl Acad Sci USA. 83 (24): 9512–6. PMID 3467321.
- ↑ Pestonjamasp KN, Pope RK, Wulfkuhle JD, Luna EJ (1997). "Supervillin (p205): A novel membrane-associated, F-actin-binding protein in the villin/gelsolin superfamily". J Cell Biol. 139 (5): 1255–69. PMID 9382871.
- ↑ Oh SW, Pope RK, Smith KP; et al. (2004). "Archvillin, a muscle-specific isoform of supervillin, is an early expressed component of the costameric membrane skeleton". J Cell Sci. 116 (Pt 11): 2261–75. doi:10.1242/jcs.00422. PMID 12711699.