7-Transmembrane proteins

Harvey, Bernard G., et al. (1976). Criteria for the Discovery of Chemical Elements. Science 193 1,271-1,272. 

Hoffman, Darleane C. (1994). The Heaviest Elements. Chemical irEngineeringNews 72 24-34. 

Hoffman, Darleane C. Ghiorso, Albert and Seaborg, Glenn T. (2000). The Transuranium People The Inside Story. London Imperial College Press. 

Hoffman, Darleane C., and Lee, Diana M. (1999). Chemistry of the Heaviest Elements One Atom at a Journal of Chemical Education 76 331-347. 

Seaborg, Glenn T. (1945). The Chemical and Radioactive Properties of the Heavy Elements. Chemical if Engineering News 23 2190-2193. 

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Example Molecular dynamics simulations of selected portions of proteins can demonstrate the motion of an amino acid sequence while fixing the terminal residues. These simulations can probe the motion of an alpha helix, keeping the ends restrained, as occurs n atiirally m transmembrane proteins. You can also investigate the conformations of loops with fixed endpoints. 

Fasman, G.D., Gilbert, W.A. The prediction of transmembrane protein sequences and their conformation an evaluation. Trends Biochem. Sci. 15 89-95, 1990. 

Proteoglycans may be soluble and located in the extracellular matrix, as is the case for serglycin, versican, and the cartilage matrix proteoglycan, or they may be integral transmembrane proteins, such as syndecan. Both types of proteoglycan... 

FIGURE 9.31 The known proteoglycans include a variety of structures. The carbohydrate groups of proteoglycans are predominantly glycosaminoglycans O-linked to serine residues. Proteoglycans include both soluble proteins and integral transmembrane proteins. 

Fasman, G. D., and Gilbert, W. A., 1990. The prediction of transmembrane protein sequences and dieir conformation An evaluation. Trends in Biochemical Sciences 15 89—92. 

The hormonal stimulation of adenylyl cyclase is effected by a transmembrane signaling pathway consisting of three components, all membrane-associated. Binding of hormone to the external surface of a hormone receptor causes a conformational change in this transmembrane protein, which in turn stimulates a GTP-binding protein (abbreviated G protein). G proteins are heterotrimeric proteins consisting of a- (45-47 kD), /3- (35 kD), and y- (7-9 kD) subunits. The a-subunit binds GDP or GTP and has an intrinsic, slow... 

Mitochondria are surrounded by a simple outer membrane and a more complex inner membrane (Figure 21.1). The space between the inner and outer membranes is referred to as the intermembrane space. Several enzymes that utilize ATP (such as creatine kinase and adenylate kinase) are found in the intermembrane space. The smooth outer membrane is about 30 to 40% lipid and 60 to 70% protein, and has a relatively high concentration of phos-phatidylinositol. The outer membrane contains significant amounts of porin —a transmembrane protein, rich in /3-sheets, that forms large channels across the membrane, permitting free diffusion of molecules with molecular weights of about 10,000 or less. Apparently, the outer membrane functions mainly to... 

Thus, Og and cytochrome c oxidase are the final destination for the electrons derived from the oxidation of food materials. In concert with this process, cytochrome c oxidase also drives transport of protons across the inner mitochondrial membrane. These important functions are carried out by a transmembrane protein complex consisting of more than 10 subunits (Table 21.2). 

The ABC-transporter superfamily represents a large group of transmembrane proteins. Members of this family are mainly involved in ATP-dependent transport processes across cellular membranes. These proteins are of special interest from a pharmacological point of... 

Most ABC-transporters, especially those located in the plasma membrane, are phosphorylated and glycosylated transmembrane proteins of different molecular weights (e.g., P-gp 170 kDa MRP2 190 kDa BCRP 72 kDa). Topologically, most ABC-transporter show a similar structure they are organized in two transmembrane domains (TMD), each consisting of six... 

APP is a type-I transmembrane protein that is part of an evolutionarily conserved protein family, including the amyloid precursor-like proteins 1 (APLP1) and 2 (APLP2). APP and APLPs are functionally redundant and form homo- and hetero-oligomers. The absence of the A 3 sequence in the APLPs underlines the importance of APP that can only give rise to the A 3 species. Decreasing the formation of soluble A 3... 

Cadherins (Calcium-dependent adhesion proteins) are transmembrane proteins, which consist of an extracellular domain composed of cadherin-repeats, a transmembrane domain, and a cytoplasmic domain that interacts with catenins and/or other cytoplasmic proteins. 

The Fas ligand or FasL is a type II transmembrane protein that belongs to the tumor necrosis factor (TNF) family. The binding of Fas ligand with its receptor induces apoptosis. 

Integrins constitute a large family of a (3 heterodimeric cell surface, transmembrane proteins that interact with a large number of extracellular matrix components through a metal ion-dependent interaction. The term integrin reflects their function in integrating cell adhesion and migration with the cystoskeleton. 

Group of transmembrane proteins engaged in the presentation of small peptide fragments to T-cells. Two classes of Major histocompatibility complex (MHC) molecules exist both of which are encoded by a highly polymorphic gene cluster. MHC class I and class II proteins present peptide fragments to CD8+ and CD4+ T-cells, respectively. The human MHC is also known as HLA, the murine MHC as H-2 complex. 

Noradrenaline transporters (NAT) are localized in the presynaptic plasma membrane of adrenergic nerve terminals. They belong to a family of proteins with 12 putative transmembrane proteins which are responsible for recycling of released neurotransmitters (noradrena-line/adrenaline, dopamine, serotonin, amino acid transmitters) back into the presynaptic nerve ending. Noradrenaline transporters can be blocked by a number of different antidepressant drags, including tricyclic antidepressants (e.g. desipramine) and selective noradrenaline reuptake inhibitors (e.g. reboxetine). 

Plexins comprise a family of transmembrane proteins that serve as receptors for semaphorins. On the basis... 

The three selectins are related both structurally and functionally. They are transmembrane proteins, with an N-terminal C-type actin domain, followed by an EGF repeat and a variable number of complement control protein (CCP) domains. Selectins bind carbohydrates, which are present in various glycoproteins. 

Semaphorins are secreted, membrane-associated or transmembrane proteins defined by the presence of a sema-phorin protein domain (Serna domain). In the mammalian system, more than 20 semaphorins have been identified which play important roles in a variety of tissues. The best characterized receptors for mediating semaphoiin effects are members of the neuropilin and plexin families of transmembrane proteins. Semaphoiin functions are best described in the regulation of neural development, angiogenesis, immunoregulation and cancer. 

Syndecans are transmembrane proteins, which are modified by the addition of heparan sulphate glycos-aminoglycan (GAG) chains and other sugars. Syndecans bind a wide variety of different ligands via their heparan sulphate chains. Binding specificities may vary depending on cell-type specific modifications of the heparan sulphate chains. 

Toll-like receptor - Transmembrane proteins involved in the recognition of components of pathogens that... 

TLRs are transmembrane proteins found on the plasma membrane and on endosomal membranes. The ability of the TLRs to recognise microbial products comes from the 19-25 copies of the LRR motif. The differences in these LRRs are what give the TLRs the ability to bind different components of pathogens. 

Besides classical receptor classes that bind endogenous or naturally occurring ligands and act via prototypical intracellular signaling cascades, a considerable number of transmembrane proteins are referred to as receptors albeit their natural ligands are unknown or they do not... 

Both tumor necrosis factor receptors (TNFR) are type I transmembrane proteins, also belonging to a large family of proteins, the TNFR superfamily... 

Cell membrane spanning proteins contain a luminal/ extracellular domain, a transmembrane region and a cytosolic domain. In a type I transmembrane protein the N-terminus is the extracellular/luminal part of the protein, whereas the C-terminus comprises the cytosolic region of the membrane protein. 

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