Interactions with plasma membrane-associated proteins

2 Interactions with plasma membrane-associated proteins 

Flavonoids inhibit enzymatic activities associated with plasma membrane and involved in lipid peroxidation. In plants and animals, major flavonoids such as quercetin inhibit 

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Besides the genomic pathway, the nongenomic pathway of AR also has been reported in oocytes (57), skeletal muscle cells (58), osteoblasts (59,60), and prostate cancer cells (61,62). As compared to the genomic pathway, the nongenomic actions of steroid receptors are characterized by the rapidity of the action, which varies from seconds to an hour or so, and by interaction with plasma membrane-associated signaling pathways (63). Nevertheless, the structural basis for nongenomic action is direct interactions between AR and cytosolic proteins from different signaling pathways, which could be closely... 

In eukaryotic cells, cyclic AMP is synthesized from ATP by the plasma membrane-bound adenylate cyclase, and modulates, through a cAMP-dependent protein kinase, metabolism and proliferation. A plasma membrane-associated adenylate cyclase from T. brucei has been purified and characterized (45). The enzyme from bloodstream forms has a neutral pH optimum, and kinetic analysis revealed a for ATP of 1.75 mM and a for Mg of 4mM. Inhibition studies indicated no effect with cAMP, but a profound inhibition by PPj, which was competitive with respect to ATP. This observation suggests that the T. brucei adenylate cyclase interacts with the phosphate portion of the ATP molecule, in contrast to adenylate cyclase in rat liver plasma membranes. Other differences between the T. brucei and mammalian adenylate cyclases were observed. For instance, the parasite enzyme activity was not stimulated by glucagon or epinephrine. Furthermore, fluoride, a potent activator of mammalian adenylate cyclase, inhibited the activity of the T. brucei enzyme. 

Hess F, Estrugo D, Fischer A et al (2007) Integrin-linked kinase interacts with caspase-9 and -8 in an adhesion-dependent manner for promoting radiation-induced apoptosis in human leukemia cells. Oncogene 26 1372-1384 Hirao M, Sato N, KondoT etal (1996) Regulation mechanism of ERM (ezrin/radixin/moesin) protein/plasma membrane association possible involvement of phosphatidylinositol turnover and Rho-dependent signaling pathway. J Cell Biol 135 37 51... 

PH domains consist of about 120 amino acid residues. They do not interact with other proteins, but associate with specific polyphosphoinositides. Consequently, PH domains appear to be important for localizing target proteins to the plasma membrane. Examples of PH domain-containing proteins include phospholipase C andpl20/RasGAP (Fig. 1). 

A second mechanism that impinges on the localization of transporters is through the association with proteins, the most prominent example being syntaxin. Syntaxin is a t-SNARE protein necessary for the fusion of vesicles with the plasma membrane (see the chapter on exocytosis). On the cell surface syntaxin consistently stabilizes the localization of GABA, noradrenaline, glycine, and 5HT transporters the PKCa isoform can sever the interaction with syntaxin suggesting a general mechanism for transporter internalization. 

Because there are no sarcomeres in smooth muscle, there are no Z lines. Instead, the actin filaments are attached to dense bodies. These structures, which contain the same protein as Z lines, are positioned throughout the cytoplasm of the smooth muscle cell as well as attached to the internal surface of the plasma membrane. Myosin filaments are associated with the actin filaments, forming contractile bundles oriented in a diagonal manner. This arrangement forms a diamond-shaped lattice of contractile elements throughout the cytoplasm. Consequently, the interaction of actin and myosin during contraction causes the cell to become shorter and wider. 

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