scholarly journals Low Molecular-weight G-actin Binding Proteins Involved in the Regulation of Actin Assembly during Myofibrillogenesis.

1997 ◽  
Vol 22 (1) ◽  
pp. 181-189 ◽  
Author(s):  
Takashi Obinata ◽  
Rie Nagaoka-Yasuda ◽  
Shoichiro Ono ◽  
Kenichi Kusano ◽  
Kurato Mohri ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Binding Proteins ◽  
Actin Binding ◽  
Low Molecular Weight ◽  
Actin Assembly ◽  
Actin Binding Proteins

Isolation of Low Molecular Weight Actin-Binding Proteins from Porcine Brain1

1984 ◽  
Vol 95 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Shohei MAEKAWA ◽  
Eisuke NISHIDA ◽  
Yasutaka OHTA ◽  
Hikoichi SAKAI
Keyword(s):  
Molecular Weight ◽  
Binding Proteins ◽  
Actin Binding ◽  
Low Molecular Weight ◽  
Actin Binding Proteins

ACTIN-BINDING PROTEINS: HOW TO REVEAL THE CONFORMATIONAL CHANGES

2008 ◽  
Vol 06 (04) ◽  
pp. 869-884
Author(s):  
NATALIA SINITSINA ◽  
IGOR ORSHANSKY ◽  
OLGA SOKOLOVA
Keyword(s):  
Conformational Changes ◽  
Binding Proteins ◽  
Electron Tomography ◽  
Protein Complexes ◽  
Intramolecular Interactions ◽  
Actin Binding ◽  
Actin Assembly ◽  
Actin Binding Proteins ◽  
Molecular Dynamics Methods ◽  
Multiple Domains

Actin is the most abundant protein in eukaryotes. Under physiological conditions, it can polymerize into polarized filaments. At the heart of these processes are actin-binding proteins that stimulate actin assembly. Most of them are composed of multiple domains that perform both regulatory and signaling functions. Many actin-binding proteins, including WASP and formin family proteins, are auto-inhibited through intramolecular interactions that mask the actin-regulating sites of these proteins. The large flexible molecules of formins have so far eluded crystallization, and have been crystallized only partially. The information from the available crystal structures is valuable, but somewhat difficult to interpret without a larger framework on which to pose the actin-binding mechanism. Single-particle electron microscopy and electron tomography could provide such a large framework with the full-length structures of protein complexes. The recent advances in determining the molecular interactions in protein complexes predict that the molecular modeling and molecular dynamics methods could be employed to study conformational changes in molecules.

The Actin Lattice: Composition, Structure and Membrane Attachment

1980 ◽  
Vol 38 ◽  
pp. 420-423
Author(s):  
J. Condeelis ◽  
J. Wolosewick
Keyword(s):  
Molecular Weight ◽  
Binding Proteins ◽  
Muscle Cells ◽  
Actin Binding ◽  
Cellular Slime Mold ◽  
Actin Binding Proteins ◽  
Cellular Slime ◽  
Composition Structure ◽  
And Control

Actin containing structures in the cytoplasm of non-muscle cells have been implicated in cell locomotion and control of the distribution of cytoplasmic and cell surface components. Consistent with this versatility of actin function is the complexity of actin containing structures that are found in non-muscle cells. Actin is a highly conserved protein with identical functional properties from cell to cell. Recently a number of actin binding proteins have been purified that may account for the assembly of actin into the different structures found in vivo. We have been investigating the actin binding proteins that are responsible for Ca++ regulated gelation of actin that was first documented in cell free extracts of Dictyostelium discoideum, a cellular slime mold. In this case these actin binding proteins will be referred to as gelation factors. Our method for purifying the gelation factors from Dictyostelium is briefly outlined as follows. Cell free extracts that contained gelation activity were fractionated with ammonium sulfate into O-45 and 45-60% pellets. Gelation activity in each pellet was purified by chromatography. The 45-60% pellet contained 95% of the gelation activity in the extract and was resolved into two gelation factors that measure 250,000 daltons and 120,000 daltons in SDS (Figure 1 b and d respectively). The remaining 5? of the gelation activity that was collected in the 0-40% pellet was recovered with a complex of 5 low molecular weight components that measure 48,000, 38,000, 32,000, 24,000 and 20,000 daltons in SDS (Figure le). The polypeptides appear to be proteolytic breakdown products of higher molecular weight gelation factors since their presence in the extract was abolished by inclusion of proteolytic inhibtors.

scholarly journals Fluorescent actin analogs with a high affinity for profilin in vitro exhibit an enhanced gradient of assembly in living cells

1994 ◽  
Vol 124 (6) ◽  
pp. 971-983 ◽  
Author(s):  
KA Giuliano ◽  
DL Taylor
Keyword(s):  
Binding Proteins ◽  
Imaging Techniques ◽  
Leading Edge ◽  
Living Cells ◽  
Actin Binding ◽  
Actin Assembly ◽  
Membrane Interface ◽  
Actin Binding Proteins ◽  
High Affinity

Constitutive centripetal transport of the actin-based cytoskeleton has been detected in cells spreading on a substrate, locomoting fibroblasts and keratocytes, and non-locomoting serum-deprived fibroblasts. These results suggest a gradient of actin assembly, highest in the cortex at the cytoplasm-membrane interface and lowest in the non-cortical perinuclear cytoplasm. We predicted that such a gradient would be maintained in part by phosphoinositide-regulated actin binding proteins because the intracellular free Ca2+ and pH are low and spatially constant in serum-deprived cells. The cytoplasm-membrane interface presents one surface where the assembly of actin is differentially regulated relative to the non-cortical cytoplasm. Several models, based on in vitro biochemistry, propose that phosphoinositide-regulated actin binding proteins are involved in local actin assembly. To test these models in living cells using imaging techniques, we prepared a new fluorescent analog of actin that bound profilin, a protein that interacts with phosphoinositides and actin-monomers in a mutually exclusive manner, with an order of magnitude greater affinity (Kd = 3.6 microM) than cys-374-labeled actin (Kd > 30 microM), yet retained the ability to inhibit DNase I. Hence, we were able to directly compare the distribution and activity of a biochemical mutant of actin with an analog possessing closer to wild-type activity. Three-dimensional fluorescence microscopy of the fluorescent analog of actin with a high affinity for profilin revealed that it incorporated into cortical cytoplasmic fibers and was also distributed diffusely in the non-cortical cytoplasm consistent with a bias of actin assembly near the surface of the cell. Fluorescence ratio imaging revealed that serum-deprived and migrating fibroblasts concentrated the new actin analog into fibers up to four-fold in the periphery and leading edge of these cells, respectively, relative to a soluble fluorescent dextran volume marker, consistent with the formation of a gradient of actin filament density relative to cell volume. Comparison of these gradients in the same living cell using analogs of actin with high and low affinities for profilin demonstrated that increased profilin binding enhanced the gradient. Profilin and related proteins may therefore function in part to bias the assembly of actin at the membrane-cytoplasm interface.

Rap1b Association with the Platelet Cytoskeleton Occurs in the Absence of Glycoproteins IIb/IIIa

1998 ◽  
Vol 79 (04) ◽  
pp. 832-836 ◽  
Author(s):  
Thomas Fischer ◽  
Christina Duffy ◽  
Gilbert White
Keyword(s):  
Molecular Weight ◽  
Divalent Cation ◽  
Binding Proteins ◽  
Binding Protein ◽  
Platelet Membrane ◽  
Low Molecular Weight ◽  
Membrane Glycoproteins ◽  
Gtp Binding Protein ◽  
Gtp Binding Proteins ◽  
Gtp Binding

SummaryPlatelet membrane glycoproteins (GP) IIb/IIIa and rap1b, a 21 kDa GTP binding protein, associate with the triton-insoluble, activation-dependent platelet cytoskeleton with similar rates and divalent cation requirement. To examine the possibility that GPIIb/IIIa was required for rap1b association with the cytoskeleton, experiments were performed to determine if the two proteins were linked under various conditions. Chromatography of lysates from resting platelets on Sephacryl S-300 showed that GPIIb/IIIa and rap1b were well separated and distinct proteins. Immunoprecipitation of GPIIb/IIIa from lysates of resting platelets did not produce rap1b or other low molecular weight GTP binding proteins and immunoprecipitation of rap1b from lysates of resting platelets did not produce GPIIb/IIIa. Finally, rap1b was associated with the activation-dependent cytoskeleton of platelets from a patient with Glanzmann’s thrombasthenia who lacks surface expressed glycoproteins IIb and IIIa. Based on these findings, we conclude that no association between GPIIb/IIIa and rap1b is found in resting platelets and that rap1b association with the activation-dependent cytoskeleton is at least partly independent of GPIIb/IIIa.

Actin-binding proteins sensitively mediate actin bundle stiffness

2006 ◽  
Vol 39 ◽  
pp. S240
Author(s):  
M. Bathe ◽  
M. Claessens ◽  
E. Frey ◽  
A. Bausch
Keyword(s):  
Binding Proteins ◽  
Actin Binding ◽  
Actin Binding Proteins ◽  
Actin Bundle

A review of actin binding proteins: new perspectives

2007 ◽  
Vol 36 (1) ◽  
pp. 121-125 ◽  
Author(s):  
Ricardo Uribe ◽  
David Jay
Keyword(s):  
Binding Proteins ◽  
Actin Binding ◽  
Actin Binding Proteins
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