Protein channels formed

Colicins are pore-forming proteins, produced by certain strains of E. coli, that kill or inhibit the growth of other, competing bacteria and even other strains of E. coli (a process known as allelopathy). Channel-forming colicins are released as soluble monomers. Upon encountering a host cell, the colicin molecule traverses the bacterial outer membrane and periplasm, then inserts itself... 

K Channels belong to a class of membrane proteins that form highly K-selective pores in membranes. All known K Channels are composed of several (usually four) pore forming alpha subunits and auxiliary beta subunits. K Channels play an essential role in cellular excitability, being involved in repolarization of Action Potentials and setting the cell resting potential as well as contributing to potassium homeostasis. 

Aquaporins Are Proteins That Form Water Channels in Certain Membranes... 

As seen in the genetic map, the genes after gene 1.1, transcribed by the T7 RNA polymerase, code for proteins that are involved in T7 DNA synthesis, the formation of virus coat proteins, and assembly. Three classes of T7 proteins are formed class I, made 4-8 minutes after infection, which use the cell RNA polymerase class II, made 6-15 minutes after infection, which are made from T7 RNA polymerase and are involved in DNA metabolism class III, made from 6 minutes to lysis, which are transcribed by T7 RNA polymerase and which code for phage assembly and coat protein. This sort of sequential pattern, commonly seen in many large double-stranded DNA phages, results in an efficient channeling of host resources, first toward DNA metabolism and replication, then on to formation of virus particles and release of virus by cell lysis. 

All cell membranes contain transmembrane proteins that form ion channels. These ion channels are usually selectively permeable to particular ions. Some channels, such as GABA-gated ion channels, are permeable to Cl ions and are inhibitory in nature because they make the inside of the nerve or muscle cells more negative as the Cl ions enter. Some ion channels are permeable to the cations Na and K, and an example of this type is the nicotinic acetylcholine-gated channel. Nicotinic channels have an excitatory effect when they open because Na ions enter and K ions leave through these channels. The cell becomes more positive inside and depolarizes. If the cell is a muscle cell, calcium accumulates in the cytoplasm and it contracts. We have found that all over the surface of Ascaris muscle there are GABA receptors (Martin, 1980) as well as nicotinic acetylcholine channels (Martin, 1982 Robertson and Martin, 1993). 

Several different changes in mitochondria occur during apoptosis. These include a change in membrane potential (usually depolarization), increased production of reactive oxygen species, potassium channel activation, calcium ion uptake, increased membrane permeability and release of cytochrome c and apoptosis inducing factor (AIF) [25]. Increased permeability of the mitochondrial membranes is a pivotal event in apoptosis and appears to result from the formation of pores in the membrane the proteins that form such permeability transition pores (PTP) may include a voltage-dependent anion channel (VDAC), the adenine nucleotide translocator, cyclophilin D, the peripheral benzodiazepine receptor, hexokinase and... 

Lyotropic lamellar (La) liquid crystals (LC), in a form of vesicle or planar membrane, are important for membrane research to elucidate both functional and structural aspects of membrane proteins. Membrane proteins so far investigated are receptors, substrate carriers, energy-transducting proteins, channels, and ion-motivated ATPases [1-11], The L liquid crystals have also been proved useful in the two-dimensional crystallization of membrane proteins[12, 13], in the fabrication of protein micro-arrays[14], and biomolecular devices[15]. Usefulness of an inverted cubic LC in the three-dimensional crystallization of membrane proteins has also been recognized[16]. 

Blair, A., Ngo, L., Park, J., Paulsen, I. T. and Saier, M. H. Jr (1996). Phylogenetic analyses of the homologous transmembrane channel-forming proteins of the FoFi-ATPases of bacteria, chloroplasts and mitochondria, Microbiology, 142, 17-32. 

During the process of cell death, cytochrome c is released from mitochondria into the cytosol where it assists to activate the caspases, a family of killer caspases that trigger cell death, hi this chapter evidence that transmission of cell death signals into the release of cytochrome c involves phospholipids at several stages will be presented. Thus, phospholipids target proapoptotic proteins to mitochondria, enable these or other proteins to form channels or pores and to break the mitochondrial permeability barrier. Finally, peroxidation or increased levels of disrupt the ability of cardiolipin to interact with cytochrome c, initiating a sequence of events that ultimately lead to cell death. 

Ion channels are large proteins which form pores through the neuronal membrane. The precise structure and function of the ion channels depend on their physiological function and distribution along the dendrites and cell body. These include specialized neurotransmitter-sensitive receptor channels. In addition, some ion channels are activated by specific metal ions such as sodium or calcium. The structure of the voltage-dependent sodium channel has been shown to consist of a complex protein with both a hydrophilic and a hydrophobic domain, the former domain occurring within the neuronal membrane while the latter domain occurs both inside and outside the neuronal membrane. 

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