Proteins connectivity

Lipoprotein fraction containing triglycerides and to a lesser degree cholesterol. VLDL is produced by the liver. The main structural protein connected to this lipoprotein class is apolipoprotein B. 

Figure 6.4 Schematic representation of the muscarinic receptor. All muscarinic receptors have seven transmembrane domains and the major difference between them is within the long cytoplasmic linkage connecting the fifth and sixth domains. This implies different G-protein connections and functions. Some possibilities are shown although the position of the Mi and M2 boxes is not intended to indicate their precise structural differences within the loop...

Heme Complex Subunit/Heme-Protein Connection Complex Subunit/Fe Ligands (in Addition to Porphyrin N Atoms) Bond Distance (A)... 

The mechanism of synthesis of polysaccharides is a controversial issue. After discovery, by Cardini s group, that starch may be polymerized on a protein,152,153 it was suggested153 that all nascent, polysaccharide chains might be covalently associated with a protein. Connected with the formation of glycoprotein is the involvement of lipid intermediates. We shall analyze the biosynthetic pathways of polysaccharides where partial or complete evidence of this kind of mechanism has been educed. 

The cytoskeletons of other eukaryotic cells typically include both microtubules and microfilaments, which consist of long, chainlike oligomers of the proteins tubulin and actin, respectively. Bundles of microfilaments often lie just underneath the plasma membrane (fig. 17.22). They participate in processes that require changes in the shape of the cell, such as locomotion and phagocytosis. In some cells, cytoskeletal microfilaments appear to be linked indirectly through the plasma membrane to peripheral proteins on the outer surface of the cell (fig. 17.23). Among the cell surface proteins connected to this network is fibronectin, a glycoprotein believed to play a role in cell-cell interactions. The lateral diffusion of fibronectin is at least 5,000 times slower than that of freely diffusible membrane proteins. 

Yang, Y., Dowling, J., Yu, Q.-C., Kouklis, P., Cleveland, D. W., and Fuchs, E. (1996). An essential cytoskeletal linker protein connecting actin microfilaments to intermediate filaments. Cell 86, 655-665. 

FIGURE 13-4 Mechanism of action of botulinum toxin at the skeletal neuromuscular junction. At a normal synapse (shown on left], fusion proteins connect acetylcholine (ACh] vesicles with the presynaptic membrane, and ACh is released via exocytosis. Botulinum toxin (represented by BTX on the right] binds to the presynaptic terminal, and enters the terminal where it destroys the fusion proteins so that ACh cannot be released. See text for details. 

The thick filament system, which comprises myosin protein, connected from the M-line to the Z-disc by titin (connectin), and myosin-binding protein C, which binds at one end to the thick filament and at the other to actin. 

Figure 1 An example of the way metallo-enzymes are under controlled formation through both controlled uptake (rejection) of a metal ion and controlled synthesis of all the proteins connected to its metabolism and functions. The example is that of iron. Iron is taken up via a molecular carrier by bacteria but by a carrier protein, transferrin, in higher organisms. Pumps transfer either free iron or transferrin into the cell where Fe + ions are reduced to Fe + ions. The Fe + ions form heme, aided by cobalamin (cobalt 2 controls) and a zinc enzyme for a-laevulinic acid (ALA) synthesis. Heme or free iron then goes into several metallo-enzymes. Free Fe + also forms a metallo-protein transcription factor, which sees to it that synthesis of all iron carriers, storage systems, metallo-proteins, and metallo-enzymes are in fixed amounts (homeostasis). There are also iron metallo-enzymes for protection including Fe SOD (superoxide dismutase). Adenosine triphosphate (ATP) and H+ gradients supply energy for all processes. See References 1 -3.

The misfolded proteins connected to neurodegenerative diseases have a strong molecular propensity to aggregate [25]. 

Recent work has been conducted to examine sweetener recognition by identifying the receptor molecules in the sweet taste receptor cells biochemically and physiologically. It is thought that intense sweeteners react with membrane receptor proteins connected to a G protein system... 

Another typical secondary structure is the p-sheet. Tertiary structure describes the spatial arrangement of amino acid residues that are far apart (such as folding of parts of the protein connected by disulfidic bonds). 

X.M. Yin, Signal transduction mediated by Bid, a pro-death Bcl-2 family protein, connects the death receptor and mitochondria apoptosis pathway. Cell Res. 10, 161-167 (2000). 

Walz, A., Dewald, B., von Tscharner, V., and Baggiolini, M. (1989). Effects of the neutrophil-activating peptide NAP-2, platelet basic protein, connective tissue-activating peptide III and platelet factor 4 on human neutrophils. J. Exp. Med. 170, 1745-1750. 

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