Membrane release

Detergent treatment of a suspension of thylakoids dissolves the membranes, releasing complexes containing both chlorophyll and protein. These chlorophyll-protein complexes represent integral components of the thylakoid membrane, and their organization reflects their roles as either light-harvesting com-... 

ATP levels and oxygen consumption [66]. Et3PAuCl treatment also reduced the potential difference across the inner mitochondrial membrane releasing sequestered calcium from mitochondria [66]. 

Fig. 9. Transport of dT and AZT through a liquid membrane released pyrimidine dT (100%) AZT ( 21 %). Reproduced with permission from Ref. (39). Copyright 1998, American Chemical Society.

Another example of molecular communication is found in a neuronal synapse, which is a communication junction between two neurons as shown in Fig.2. The presynaptic membrane releases the neurotransmitter molecule that is recognized and captured by the receptor located on the surface of the postsynaptic membrane. 

The membrane release and the deposition of the sensitive layer are identical with the process described in Sect. 4.1.2. 

The first device was a circular-shape microhotplate, which essentially consisted of CMOS-process materials (Sect. 4.1). The fabrication of this microhotplate required a minimum of post-CMOS processing steps. The electrochemical etching process used for the membrane release and the formation of the circular-shape Si island was optimized and can now be routinely apphed on wafer-level. 

Mechanism of Action An anti-infective that acts upon cell wall and cell membrane. Releases silver slowly in concentrations selectively toxic to bacteria. Therapeutic Effect Produces bactericidal effect. 

FIGURE 11-24 Fusion induced by the hemagglutinin (FIA) protein during viral infection. HA protein is exposed on the membrane surface of the influenza virus. When the virus moves from the neutral pH of the interstitial fluid to the low-pH compartment (endosome) in the host cell, HA undergoes dramatic shape changes that mediate fusion of the viral and endosomal membranes, releasing the viral contents into the cytoplasm. 

Assembly of chylomicrons The enzymes involved in triacylglycerol, cholesterol, and phospholipid synthesis are located in Ihe smooth ER. Assembly of the apolipoproteins and lipid into chylomicrons requires microsomal triacylglycerol transfer protein (see p. 229), which loads apo B-48 with lipid. This occurs during transition from the ER to the Golgi, where the particles are packaged in secretory vesicles. These fuse with the plasma membrane releasing the lipoproteins, which then enter the lymphatic system and, ultimately, the blood. 

Figure 10.8 Milk lipid globule membranes released by churning of washed globules and collected by ultracentrifugation retain densely staining coal material along one face of the bilayer membrane. As seen in this electron micrograph of glutaraldehyde and osmium tetroxide-fixed material, the...

Ultrasonic waves, produced by a sonicator, are transmitted into a suspension of cells by a metal probe (Figure E4.1C). The vibration set up by the ultrasonic waves disrupts the cell membrane, releasing the cell components into the surrounding aqueous solution. 

A general scheme showing how electron transport can result in proton translocation. A, B, D, and E are electron carriers that bind protons when they are reduced. A and D undergo reduction to AH2 and DH2 on the matrix side of the membrane, picking up protons from the solution on this side. They then transfer protons along with electrons to B and E. BH2 and EII are reoxidized on the opposite side of the membrane, releasing protons here. Electrons move without protons from BH2 to D. 

Like spinal cord trauma, traumatic head injury consists of a primary injury, attributable to the mechanical insult itself, and a secondary injury, attributable to the series of systemic and local neurochemical changes that occur in brain after the initial traumatic insult (Klussmann and Martin-Villalba, 2005). The primary injury causes a rapid deformation of brain tissues, leading to rupture of neural cell membranes, release of intracellular contents, and disruption of blood flow and breakdown of the blood-brain barrier. In contrast, secondary injury to the brain tissue includes many neurochemical alterations such as release of cytokines, glial cell reactions involving both activated microglia and astroglia, and demyelination... 

FIGURE 23.7 Dopamine (DA) is synthesized within neuronal terminals from the precursor tyrosine by the sequential actions of the enzymes tyrosine hydroxylase, producing the intermediary L-dihydroxyphenylalanine (Dopa), and aromatic L-amino acid decarboxylase. In the terminal, dopamine is transported into storage vesicles by a transporter protein (T) associated with the vesicular membrane. Release, triggered by depolarization and entry of Ca2+, allows dopamine to act on postsynaptic dopamine receptors (DAR). Several distinct types of dopamine receptors are present in the brain, and the differential actions of dopamine on postsynaptic targets bearing different types of dopamine receptors have important implications for the function of neural circuits. The actions of dopamine are terminated by the sequential actions of the enzymes catechol-O-methyl-transferase (COMT) and monoamine oxidase (MAO), or by reuptake of dopamine into the terminal. 

Plasmid/cationic carrier complexes have been proposed to internalize into the endosome and initiate the destabilization of endosomal membranes. This destabilization would induce diffusion of anionic lipids from the external layer of the endosomal membrane into the complexes and form charge neutralized ion pairs with the cationic lipids. Destabilization and/or fusion of the complex with the plasma membrane would permit the same anionic lipids to diffuse to the surface, as would fusion with the endosomal membrane. Release of the condensed DNA from the cationic lipid in the endosome is likely to generate a mechanical or osmotic stress that raptures the endosomal bilayer and releases DNA into the cytoplasm. In contrast, DNA release from complexes on the cell surface might be unable to stress the membrane to a degree sufficient to rapture. 

Figure 12.41. Neurotransmitter Release. Neurotransmitter-containing synaptic vesicles are arrayed near the plasma membrane of a nerve cell. Synaptic vesicles fuse with the plasma membrane, releasing the neurotransmitter into the synaptic cleft. [T. Reese/Don Fawcett/ Photo Researchers.]...

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