Guanylate kinase, structure

Adaptor Proteins. Figure 1 Adaptor protein domains. A scheme of the domain structures of some well-characterized adaptor proteins is shown. Descriptions of domain characteristics are in main text except C2, binds to phospholipids GTPase activating protein (GAP) domain, inactivates small GTPases such as Ras Hect domain, enzymatic domain of ubiquitin ligases and GUK domain, guanylate kinase domain. For clarity, not all domains contained within these proteins are shown. 

Stehle, T. Schultz, G.E. Three-dimensional structure of the complex of guanylate kinase from yeast with its substrate GMP. J. Mol. Biol., 211, 249-254 (1990)... 

Blaszczyk, J. Li, Y Yan, H. Ji, X. Crystal structure of unligated guanylate kinase from yeast reveals GMP-induced conformational changes. J. Mol. Biol., 307, 247-257 (2001)... 

Sekulic, N. Shuvalova, L. Spangenberg, O. Konrad, M. Lavie, A. Structural characterization of the closed conformation of mouse guanylate kinase. J. Biol. Chem., 277, 30236-30243 (2002)... 

Acyclovir (ACV) is not a true nucleoside, because the guanine residue is attached to an open-chain structure, but it mimics deoxyribose well enough for the compound to be accepted as a substrate by a thymidine kinase specified by certain herpes-type viruses. The normal thymidine kinase in mammalian cells does not recognize ACV as a substrate, however, so only virus-infected cells convert ACV to its monophosphate. Once the first phosphate has been added, the second phosphate is added by cellular guanylate kinase several other cellular kinases can add the third phosphate. The triphosphate is a more potent inhibitor of the viral DNA polymerases than of cellular DNA polymerases and also inactivates the former but not the latter. The net result is that ACV has been an effective treatment of, and prophylaxis for, genital herpes. Also it can result in dramatic relief of pain associated with shingles caused by reactivation of latent varicella-zoster virus, and has been successful in many patients with herpes encephalitis. 

The calcium channel p subunit is the only calcium channel subunit for which there is crystal structure information. The core of this subunit is homologous to membrane-associated guanylate kinases (MAGUKs), with conserved, interacting SH3 and guanylate kinase (GK) domains (Takahashi et al. 2004). Residues in the... 

Figure 9.46. Structures of Adenylate Kinase and Guanylate Kinase. The nucleoside triphosphate-binding domain is a common feature in these and other homologous nucleotide kinases. The domain consists of a central P-pleated sheet surrounded on both sides by a helices (highlighted in purple) as well as a key loop (shown in green).

Structural and Functional Roles of Tyrosine-50 of Yeast Guanylate Kinase... 

Diacylglycerol, on the other hand, is lipid soluble and remains in the lipid bilayer of the membrane. There it can activate protein kinase C (PKC), a very important and widely distributed enzyme which serves many systems through phosphorylation, including neurotransmitters (acetylcholine, a,- and P-adrenoceptors, serotonin), peptide hormones (insulin, epidermal growth hormone, somatomedin), and various cellular functions (glycogen metabolism, muscle activity, structural proteins, etc.), and also interacts with guanylate cyclase. In addition to diacylglycerol, another normal membrane lipid, phos-phatidylserine, is needed for activation of PKC. The DG-IP3 limbs of the pathway usually proceed simultaneously. 

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