Actin dependent

The membrane tubules and lamellae of the endoplasmic reticulum (ER) are extended in the cell with the use of MTs and actin filaments. Kinesin motors are required for stretching out the ER, whereas depolymerization of microtubules causes the retraction of the ER to the cell centre in an actin-dependent manner. Newly synthesized proteins in the ER are moved by dynein motors along MTs to the Golgi complex (GC), where they are modified and packaged. The resulting vesicles move along the MTs to the cell periphery transported by kinesin motors. MTs determine the shape and the position also of the GC. Their depolymerization causes the fragmentation and dispersal of the GC. Dynein motors are required to rebuild the GC. 

The cytochalasins are a group of metabolites produced by certain fungi (e.g., Helminthosporium dermatoideum) that inhibit actin-dependent types of cell movement such as leukocyte locomotion, phagocytosis, cytokinesis, the retraction of... 

Kinosian, H.J., Selden, L.A., Estes. J.E., Gershman, L.C. (1993). Nucleotide binding to actinication dependence of nucleotide dissociation and exchange rates. J. Biol. Chem. 268, 8683-8691. 

Inhibitor of F-actin-myosin interaction (inhibitor of F-actin-dependent activation of ATPase) Troponin system (Tpl) Unphosphorylated myosin light chain... 

Jolly C, Kashefi K, Hollinshead M, Sattentau QJ. HIV-1 cell to cell transfer across an Env-induced, actin-dependent synapse. J Exp Med 2004 199(2) 283-293. 

Iyengar S, Hildreth JE, Schwartz DH. Actin-dependent receptor colocalization required for human immunodeficiency virus entry into host cells. J Virol 1998 72(6) 5251—5255. 

Phagocytosis and macropinocytosis are actin-dependent and clathrin-independent processes that lead to the uptake of particles into large vesicles. 

Because of the strict requirement for actin, the most commonly used inhibitors of macropinocytosis are the cytochalasins, especially cytochalasin D or toxin C. These substances also block phagocytosis and intracellular trafficking along actin filaments. Therefore, the results from these experiments are described in the trafficking section Actin Dependence on Liposome Uptake. ... 

Morales M, Colicos MA, Goda Y. Actin-dependent regulation of neurotransmitter release at central synapses. Neuron 2000 27(3) 539-550. 

Phagotrophy is a fourth means by which the parasite captures Hb. Many phagosomes appear at the trophozoite and schizont stages. Unlike typical phagosome found in other eukaryotes, their formation is not actin-dependent and very similar in mechanism to the big gulp [21]. 

M., Madden, D.T. et al.. Interaction of Slap2p s ANTH domain with PtdIns(4,5)P2 is important for actin-dependent endocytotic internalization, Mol. Biol. Cell 16, 717-730, 2005 Yao, P.J., Bushlin, I., and Petralia, R.S., Partially overlapping distribution of epsinl and HIPl at the synapse analysis by immunoelectron microscopy, J. Comp. Neurol. 494, 368-379, 2006. 

Actin-dependent propulsion of endosomes and lysosomes by recmitment of N-WASP J. Cell Biol. 148, 519-530. 

Rosentretcr A, Hofmann A, Xavier CP et al. Coronin 3 involvement in F-actin-dependent processes at... 

The seven mammahan coronins exhibit a distinct pattern of expression across cell types and tissues. The best-characterized CRN4/CORO 1A is virtually exclusively expressed in thymocytes, T-cells, macrophages and ncutrophils. It has been shown to function in actin-dependent processes as well as in specific functions unrelated to actin. For a detailed view on mammahan CORO 1A regarding its interaction with actin please refer to Chapters 5 and 6 and to Chapter 11,5th section, for details regarding actin-unrelated functions please refer to Chapter 10 and also Chapter 11,5 th section. 

Alternately, evidence also exists that Coronin lA s role may be to control calcium dynamics after bacterial infection. Macrophages from mice lacking Coronin lA do not display the persistent increase in calcium levels that are normally displayed after infection. This consequently prevents the activation of signaling pathways via proteins such as the calcium-sensitive phosphatase Calcineurin. While no alterations in actin dependent processes have been detected in Coronin lA null macrophages, the effects may be linked to more subtle effects on actin that affect the known relationship between cytoskeletal dynamics and calcium trafficking. Dramatic effects on actin-dependent processes may also be masked by the presence of functionally redundant Coronin isoforms in this cell type. 

ADP-ribosylation of actin depends on the native structure of the protein substrate. In the presence of EDTA, which chelates and removes the actin-bound magnesium ion, resulting in denaturation of actin, ADP-ribosylation is completely blocked (Just ef al., 1990). C. botulinum C2 toxin or C. perfringens iota toxin ADP-ribosylate monomeric G-actin, but not polymerized F-actin (Aktories et al., 1986b Schering et al., 1988). This is due to the fact that the acceptor amino acid arginine-177, which is located in domain III of actin, is at or near... 

Actin dependent Actin dependent Actin dependent... 

An alternative view of the source of cochlear amplification is that it arises in the OHC s bundles of stereocilia. The stereocilia bundle is composed of many actin filaments, and the kinocilium containing mainly axonemal microtubules. At least three types of actin-dependent molecular motor proteins are expressed in the stereocilia and are involved in adaptation of the hair cell MET channels myosin 15A (Rzadzinska et al., 2004), myosin 7A (Kros et al., 2002), and myosin 1C (Gillespie and Cyr, 2004). Many studies have shown that fast adaptation of MET channels can amplify the oscillation of hair bundles in the nonmammalian auditory... 

In vitro, the presence of physiological salt concentrations causes G-actin to polymerize to form the F-actin helix, which in native thin filaments represents the backbone of the filament. Polymerization of G-actin into F-actin can be followed by measuring lightscattering or by viscometry measurements. As in skeletal muscle, polymerization of smooth muscle actin depends on actin concentration, temperature, and ionic conditions (Strzelecka-Golaszewska et al., 1980). For both gizzard and bovine aortic muscle actin, the polymerization rate is optimal at 100 mM KCl and 1 mM MgCl2 (Cavadore et al., 1985). 

It has been established for several years that the major mechanism for regulation of contraction in smooth muscle is myosin phosphorylation (Hart-shorne, 1987). Phosphorylation of the two 20,000-dalton light chains of myosin (LC20) activates the actin-dependent ATPase activity of myosin and this initiates the contractile response. Dephosphorylated myosin is associated with relaxed muscle. In this scheme there are two key enzymes the myosin light chain kinase (MLCK) and the myosin light chain phosphatase (MLCP). Obviously a balance of these two activities determines the level of myosin phosphorylation. 

It thus seems true to say that the extractability of L-myosin and actin depends solely on the mutual combination of these proteins, and the hindrance to diffusion by the surrounding muscle structures (cf. Dubuisson, 1947). 

Myosin, an essential protein component of contractile muscle together with actin. Myosins are eukaryotic actin-dependent molecular motors with high importance for a wide range of functions such as muscle contraction, vision, hearing, cell motility, and host cell invasion of apicomplexan parasites. Myosin forms almost entirely the... 

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