Proteins membrane component

Organism Outer membrane receptor Binding protein Membrane component ATP-binding component Substrates References... 

Toxicity of het ologous genes in E. coli (such as genes specifying secretion proteins, membrane components). 

A receptor is a surface membrane component, usually a protein, which regulates some biological event in response to reversible binding of a relatively small molecule40 . The precise three-dimensional structures of the binding sites of receptors still remain unknown today. Thus, this section mainly describes the correlation of shape similarity between the molecules which would bind to a given receptor with their biological activity. 

Disorder characterized by atrophy ofthe choroid (the thin membrane covering most of the posterior of the eye between the retina and sclera) and degeneration of the retinal pigment epithelium resulting in night blindness. The disease is caused by mutations in Rab escort protein Repl (component A of Rab geranylgeranyl transferase). 

The use of Upid bilayers as a relevant model of biological membranes has provided important information on the structure and function of cell membranes. To utilize the function of cell membrane components for practical applications, a stabilization of Upid bilayers is imperative, because free-standing bilayer lipid membranes (BLMs) typically survive for minutes to hours and are very sensitive to vibration and mechanical shocks [156,157]. The following concept introduces S-layer proteins as supporting structures for BLMs (Fig. 15c) with largely retained physical features (e.g., thickness of the bilayer, fluidity). Electrophysical and spectroscopical studies have been performed to assess the appUcation potential of S-layer-supported lipid membranes. The S-layer protein used in aU studies on planar BLMs was isolated fromB. coagulans E38/vl. 

The process by which cells take up large molecules is called endocytosis. Some of these molecules (eg, polysaccharides, proteins, and polynucleotides), when hydrolyzed inside the cell, yield nutrients. Endocytosis provides a mechanism for regulating the content of certain membrane components, hormone receptors being a case in point. Endocytosis can be used to learn more about how cells function. DNA from one cell type can be used to transfect a different cell and alter the latter s function or phenotype. A specific gene is often employed in these experiments, and this provides a unique way to smdy and analyze the regulation of that gene. DNA transfection depends upon endocytosis endocy-... 

Primary and secondary products, and end-products of lipid peroxidation have all been shown to accumulate in senile cataracts (Babizhayev, 1989b Simonelli et al., 1989). Accumulation of these compounds in the lenticular epithelial membranes is a possible cause of damage preceding cataract formation. In senile cataracts there is also extensive oxidation of protein methionine and cysteine in both the membrane and cytosol components (Garner and Spector, 1980), while in aged normal lenses a lesser extent of oxidation was confined to the membrane. The authors therefore suggested that oxidation of membrane components was a precataract state. 

Assembly of nucleic acid and protein subunits (and membrane components in enveloped viruses) into new virus particles ... 

Structural changes of Rn/Rn-d exposed lung cells similar to heat symptoms can be interpreted as being caused by the similar underlying mechanism, e.g. re-arrangements of membrane protein-lipid components, and by releasing some of the attachment points of the cell to the petridish-surface. 

Prossnitz, E., Nikaido, K., Ulbrich, S.J., and Ames, G.F. (1988) Formaldehyde and photoactivatable cross-linking of the periplasmic binding protein to a membrane component of the histidine transport system of Salmonella typhimurium. J. Biol. Chem. 263, 17917-17920. 

Retrieval of membrane components in the secretory pathway through receptor-mediated endocytosis (RME) is a clathrin-coat-dependent process [5]. The clathrin coat provides stability to the vesicle core and allows uptake of specific membrane proteins for reuse or degradation. RME shows a remarkable degree of specificity, allowing cells to internalize with astonishing efficiency only those selected molecules independent of their extracellular concentration. 

Specific membrane components must be delivered to their sites of utilization and not left at inappropriate sites [3]. Synaptic vesicles and other materials needed for neurotransmitter release should go to presynaptic terminals because they serve no function in an axon or cell body. The problem is compounded because many presynaptic terminals are not at the end of an axon. Often, numerous terminals occur sequentially along a single axon, making en passant contacts with multiple targets. Thus, synaptic vesicles cannot merely move to the end of axonal MTs. Targeting of synaptic vesicles thus becomes a more complex problem. Similar complexities arise with membrane proteins destined for the axolemma or a nodal membrane. 

Unlike the simple example of the solution described above, a human body is a complex mixture of components (tissues, proteins, membranes, etc.). Yet, in human pharmacokinetic studies, with rare exceptions only the plasma... 

Proteins represent another major group of membrane components. They play structural roles and/or are involved in many cellular processes, which are strictly coupled to membranes. Proteins can be either entirely embedded within the bilayer, or they might be firmly anchored (e.g. by a hydrophobic transmembrane segment composed of hydrophobic amino acid side-chains or as lipoprotein), or they can be just associated with the surface. 

Dassa, E. and Hofnung, M. (1985). Sequence of gene malG in E. coli K12 homologies between integral membrane components from binding protein-dependent transport systems, EMBO J., 9, 2287-2293. 

Figure 4.13. Model of peptide initiation of mast secretion. Insertion of the hydrophobic region of the peptide into the lipid bilayer properly orients the basic (+) groups at the N-terminus for binding to negatively charged membrane components. As a result, there is activation of the G protein complex with the subsequent generation of inositol triphosphate (IP ) and diacylglycerol (DAG). These intermediates then stimulate the mobilization of cellular Ca and possibly the transient influx of extracellular Ca as well as the activation ofprotein kinase C. As a consequence, the level of intracellular free ionized Ca is maintained at an elevated state. The end result is the exocytotic extrusion of secretory granules.

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