Guanosine-51-diphosphate

Guanosine, 2, 3 -0-isopropylidene-5 -trityl-dipole moment, 5, 522 (B-72MI40902, p. 72) Guanosine diphosphate pK 5, 525 (56MI40900)... 

Figure 47-7. Pathway of biosynthesis of dolichol-P-P-oligosaccharide. The specific linkages formed are indicated in Figure 47-8. Note that the first five internal mannose residues are donated by GDP-mannose, whereas the more external mannose residues and the glucose residues are donated by dolichol-P-mannose and dolichol-P-glucose. (UDP, uridine diphosphate Dol, dolichol P, phosphate UMP, uridine monophosphate GDP, guanosine diphosphate M, mannose G, glucose.)...

Figure 12 Gradient separation of bases, nucleosides and nucleoside mono- and polyphosphates. Column 0.6 x 45 cm. Aminex A-14 (20 3 p) in the chloride form. Eluent 0.1 M 2-methyl-2-amino-l-propanol delivered in a gradient from pH 9.9-100 mM NaCl to pH 10.0-400 mM NaCl. Flow rate 100 ml/hr. Temperature 55°C. Detection UV at 254 nm. Abbreviations (Cyt) cytosine, (Cyd) cytidine, (Ado) adenosine, (Urd) uridine, (Thyd) thymidine, (Ura) uracil, (CMP) cytidine monophosphate, (Gua) guanine, (Guo) guanosine, (Xan) xanthine, (Hyp) hypoxanthine, (Ino) inosine, (Ade) adenosine, (UMP) uridine monophosphate, (CDP) cytidine diphosphate, (AMP) adenosine monophosphate, (GMP) guanosine monophosphate, (IMP) inosine monophosphate, (CTP) cytidine triphosphate, (ADP) adenosine diphosphate, (UDP) uridine monophosphate, (GDP) guanosine diphosphate, (UTP) uridine triphosphate, (ATP) adenosine triphosphate, (GTP), guanosine triphosphate. (Reproduced with permission of Elsevier Science from Floridi, A., Palmerini, C. A., and Fini, C., /. Chromatogr., 138, 203, 1977.)...

Another triphosphate synthesis is described in reference [94], where a partially protected hexaribonucleotide derivative is converted by CDI into the imidazolide and subsequently condensed with a protected 7-methyl guanosine diphosphate to give the triphosphate. 

The activated receptor combines with the G-protein in its Ggdp form, with the consequence that guanosine triphosphate (GTP) can replace previously bound guanosine diphosphate (GDP). The extent to which this can occur will be influenced by the local concentration of GTP. 

The most common second messenger activated by protein/peptide hormones and catecholamines is cyclic adenosine monophosphate (cAMP). The pathway by which cAMP is formed and alters cellular function is illustrated in Figure 10.1. The process begins when the hormone binds to its receptor. These receptors are quite large and span the plasma membrane. On the cytoplasmic surface of the membrane, the receptor is associated with a G protein that serves as the transducer molecule. In other words, the G protein acts as an intermediary between the receptor and the second messengers that will alter cellular activity. These proteins are referred to as G proteins because they bind with guanosine nucleotides. In an unstimulated cell, the inactive G protein binds guanosine diphosphate (GDP). When the hormone... 

G proteins comprise several families of diverse cellular proteins that subserve an equally diverse array of cellular functions. These proteins derive their name from the fact that they bind the guanine nucleotides guanosine triphosphate (GTP) and guanosine diphosphate (GDP) and possess intrinsic GTPase activity. G proteins play a central role in signal transduction as well as in a myriad of cellular processes, including membrane vesicle transport,... 

All GTP binding proteins in signal transduction share a common structural element - the Ras-like domain which is responsible for the specific complexation of guanosine diphosphate and -triphosphate and which contains catalytic residues that promote GTP-hydrolysis. 

Guanine Guanosine GuanyUc acid Guanosine monophosphate (GMP) Guanosine diphosphate (GDP) Guanosine triphosphate (GTP)... 

Figure 2.4. Relationship between the postsynaptic receptor and the secondary messenger system. GTP=guanosine triphosphate GDP=guanosine diphosphate ATP=adenosine triphosphate AMP=adenosine monophosphate.

During the past 15 years data from experiments with different types of animal tissues and micro-organisms, using intact cells, crude extracts or purified enzymes, have firmly established the general occurrence of nucleotide reductases and have stressed their importance for DNA synthesis in essentially all types of rapidly growing cells [54]. It has been proposed that ribonucleotide diphosphates lose a hydroxide ion from C-2 to form a carbonium ion which is then stero-specifically reduced by a hydride ion derived from thioredoxin [54]. Adenosine diphosphate and guanosine diphosphate (as well as uridine and cytidine diphosphates) are reduced in this manner. 

R7. Richards, J. B., Evans, P. J., and Hemming, F. W., Dolichol phosphates as acceptors of mannose from guanosine diphosphate mannose in liver systems. Biochem. J. 124, 957-959 (1971). 

Defect in transport or production of guanosine diphosphate L-fucose. Without the carbohydrate L-fucose, interaction of neutrophils with P- and E-selectins on endofiielial cells is affected. 

There are several intracellular second messengers that are activated by metabotropic receptors, also referred to as G protein-coupled receptors (Duman and Nestler 1999). These receptors couple with G proteins that are heterotrimers made up of a-, (3- and y-subunits. Interaction of the G protein heterotrimer with activated receptor increases the exchange of guanosine triphosphate (GTP) for bound guanosine diphosphate (GDP), resulting in dissociation of the heterotrimer into free a and (3y subunits that in turn can regulate second messen-... 

Galactose and arabinose of unknown configuration were obtained after hydrolysis of a guanosine diphosphate sugars fraction from pig milk.85 A similar fraction from strawberry leaves produced a considerable proportion of D-xylose.69... 

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