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This is the Wikipedia entry entitled "Gamma-glutamyl transpeptidase". More...
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Gamma-glutamyl transpeptidase Edit Wikipedia article
|PDB structures||RCSB PDB PDBe PDBsum|
|Gene Ontology||AmiGO / EGO|
|Locus||Chr. 22 q11.1-11.2|
|Locus||Chr. 22 q11.1-11.2|
Gamma-glutamyl transferase or gamma-glutamyl transpeptidase (also γ-glutamyl transferase, GGT, GGTP, gamma-GT) (EC 188.8.131.52) is an enzyme that transfers gamma-glutamyl functional groups. It is found in many tissues, the most notable one being the liver, and has significance in medicine as a diagnostic marker.
GGT catalyzes the transfer of the gamma-glutamyl moiety of glutathione to an acceptor that may be an amino acid, a peptide or water (forming glutamate). GGT plays a key role in the gamma-glutamyl cycle, a pathway for the synthesis and degradation of glutathione and drug and xenobiotic detoxification. Other lines of evidence indicate that GGT can also exert a prooxidant role, with regulatory effects at various levels in cellular signal transduction and cellular pathophysiology.
GGT is present in the cell membranes of many tissues, including the kidneys, bile duct, pancreas, gallbladder, spleen, heart, brain, and seminal vesicles. It is involved in the transfer of amino acids across the cellular membrane and leukotriene metabolism. It is also involved in glutathione metabolism by transferring the glutamyl moiety to a variety of acceptor molecules including water, certain L-amino acids, and peptides, leaving the cysteine product to preserve intracellular homeostasis of oxidative stress. This general reaction is:
- (5-L-glutamyl)-peptide + an amino acid peptide + 5-L-glutamyl amino acid
In prokaryotes and eukaryotes, it is an enzyme that consists of two polypeptide chains, a heavy and a light subunit, processed from a single chain precursor by an autocatalytic cleavage. The active site of GGT is known to be located in the light subunit.
GGT is predominantly used as a diagnostic marker for liver disease in medicine, latent elevations in GGT are typically seen in patients with chronic viral hepatitis infections often taking 12 months or more to present.
Elevated serum GGT activity can be found in diseases of the liver, biliary system, and pancreas. In this respect, it is similar to alkaline phosphatase (ALP) in detecting disease of the biliary tract. Indeed, the two markers correlate well, though there is conflicting data about whether GGT has better sensitivity. In general, ALP is still the first test for biliary disease. The main value of GGT over ALP is in verifying that ALP elevations are, in fact, due to biliary disease; ALP can also be increased in certain bone diseases, but GGT is not. More recently, slightly elevated serum GGT has also been found to correlate with cardiovascular diseases and is under active investigation as a cardiovascular risk marker. GGT in fact accumulates in atherosclerotic plaques, suggesting a potential role in pathogenesis of cardiovascular diseases, and circulates in blood in the form of distinct protein aggregates, some of which appear to be related to specific pathologies such as metabolic syndrome, alcohol addiction and chronic liver disease. High body mass index is associated with type 2 diabetes only in persons with high serum GGT.
GGT is elevated by large quantities of alcohol ingestion. However, determination of high levels of total serum GGT activity is not specific to alcohol intoxication, and the measurement of selected serum forms of the enzyme offer more specific information. Isolated elevation or disproportionate elevation compared to other liver enzymes (such as ALP or ALT) can indicate alcohol abuse or alcoholic liver disease. and can indicate excess alcohol consumption up to 3 or 4 weeks prior to the test. The mechanism for this elevation is unclear. Alcohol might increase GGT production by inducing hepatic microsomal production, or it might cause the leakage of GGT from hepatocytes.
Numerous drugs can raise GGT levels, including barbiturates and phenytoin. GGT elevation has also been occasionally reported following NSAIDs, St. John's wort, Kava, and aspirin. Elevated levels of GGT can also be due to congestive heart failure.
Individual test results should always be interpreted using the reference range from the laboratory that performed the test though example reference ranges are 15-85 IU/L for men, and 5-55 IU/L for women.
Human proteins that belong to this family include:
- Tate SS, Meister A (1985). "gamma-Glutamyl transpeptidase from kidney". Methods in Enzymology 113: 400–419. doi:10.1016/S0076-6879(85)13053-3. ISBN 978-0-12-182013-8. PMID 2868390.
- Courtay C, Oster T, Michelet F, Visvikis A, Diederich M, Wellman M, et al. (Jun 1992). "Gamma-glutamyltransferase: nucleotide sequence of the human pancreatic cDNA. Evidence for a ubiquitous gamma-glutamyltransferase polypeptide in human tissues". Biochemical Pharmacology 43 (12): 2527–2533. doi:10.1016/0006-2952(92)90140-E. PMID 1378736.
- Dominici S, Paolicchi A, Corti A, Maellaro E, Pompella A (2005). "Prooxidant reactions promoted by soluble and cell-bound γ-glutamyltransferase activity". Meth. Enzymol. 401: 483–500. doi:10.1016/S0076-6879(05)01029-3. PMID 16399404.
- Goldberg, DM (1980). "Structural, functional, and clinical aspects of gamma-glutamyltransferase". Crit Rev Clin Lab Sci 12 (1): 1–58. doi:10.3109/10408368009108725. PMID 6104563.
- Meister A (August 1974). "The gamma-glutamyl cycle. Diseases associated with specific enzyme deficiencies". Ann. Intern. Med. 81 (2): 247–53. doi:10.7326/0003-4819-81-2-247. PMID 4152527.
- Raulf M, Stüning M, König W (May 1985). "Metabolism of leukotrienes by L-gamma-glutamyl-transpeptidase and dipeptidase from human polymorphonuclear granulocytes". Immunology 55 (1): 135–47. PMC 1453575. PMID 2860060.
- Schulman JD, Goodman SI, Mace JW, Patrick AD, Tietze F, Butler EJ (July 1975). "Glutathionuria: inborn error of metabolism due to tissue deficiency of gamma-glutamyl transpeptidase". Biochem. Biophys. Res. Commun. 65 (1): 68–74. doi:10.1016/S0006-291X(75)80062-3. PMID 238530.
- Yokoyama H (June 2007). "[Gamma glutamyl transpeptidase (gammaGTP) in the era of metabolic syndrome]". Nihon Arukoru Yakubutsu Igakkai Zasshi (in Japanese) 42 (3): 110–24. PMID 17665541.
- Lim JS, Lee DH, Park JY, Jin SH, Jacobs DR (Jun 2007). "A strong interaction between serum gamma-glutamyltransferase and obesity on the risk of prevalent type 2 diabetes: results from the Third National Health and Nutrition Examination Survey". Clinical Chemistry 53 (6): 1092–1098. doi:10.1016/j.jacl.2011.05.004. PMID 17478563.
- Betro MG, Oon RC, Edwards JB (November 1973). "Gamma-glutamyl transpeptidase in diseases of the liver and bone". Am. J. Clin. Pathol. 60 (5): 672–8. PMID 4148049.
- Lum G, Gambino SR (April 1972). "Serum gamma-glutamyl transpeptidase activity as an indicator of disease of liver, pancreas, or bone". Clin. Chem. 18 (4): 358–62. PMID 5012259.
- Emdin M, Pompella A, Paolicchi A (2005). "Editorial - Gamma-glutamyltransferase, atherosclerosis, and cardiovascular disease: triggering oxidative stress within the plaque". Circulation 112 (14): 2078–80. doi:10.1161/CIRCULATIONAHA.105.571919. PMID 16203922.
- Pompella A, Emdin M, Passino C, Paolicchi A (2004). "The significance of serum gamma-glutamyltransferase in cardiovascular diseases". Clin. Chem. Lab. Med. 42 (10): 1085–91. doi:10.1515/CCLM.2004.224. PMID 15552264.
- Franzini M, Bramanti E, Ottaviano V, Ghiri E, Scatena F, Pompella A, et al. (2006). "A high performance gel filtration chromatography method for gamma-glutamyltransferase fraction analysis". Anal. Biochem. 374: 1–8. doi:10.1016/j.ab.2007.10.025. PMID 18023410.
- Lamy J, Baglin MC, Ferrant JP, Weill J (1974). "Determination de la gamma-glutamyl transpeptidase senque des ethyliques a la suite du sevrage". Clin Chim Acta 56: 169. doi:10.1016/0009-8981(74)90225-3.
- Kaplan MM; et al. (1985). Chang NC, Chan NM, ed. Biochemical basis for serum enzyme abnormalities in alcoholic liver disease. Research Monograph No. 17 (in Early identification of alcohol abuse) (NIAAA). p. 186.
- Barouki R, Chobert MN, Finidori J, Aggerbeck M, Nalpas B, Hanoune J (1983). "Ethanol effects in a rat hepatoma cell line: induction of gamma-glutamyltransferase". Hepatology 3 (3): 323–9. doi:10.1002/hep.1840030308. PMID 6132864.
- Rosalki SB, Tarlow D, Rau D (August 1971). "Plasma gamma-glutamyl transpeptidase elevation in patients receiving enzyme-inducing drugs". Lancet 2 (7720): 376–7. doi:10.1016/S0140-6736(71)90093-6. PMID 4105075.
- "Kava Uses, Benefits & Dosage". Herbal Database. Drugs.com.
- Ruttmann E, Brant LJ, Concin H, Diem G, Rapp K, Ulmer H (October 2005). "Gamma-glutamyltransferase as a risk factor for cardiovascular disease mortality: an epidemiological investigation in a cohort of 163,944 Austrian adults". Circulation 112 (14): 2130–7. doi:10.1161/CIRCULATIONAHA.105.552547. PMID 16186419.
- General Laboratory Manual (PDF). Department of Pathology, Hackensack University Medical Centre. 2012. p. 129. Retrieved 20 Feb 2014.
- MedlinePlus Encyclopedia 003458
- gamma-Glutamyltransferase at the US National Library of Medicine Medical Subject Headings (MeSH)
- GGT - Lab Tests Online
This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.
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This tab holds annotation information from the InterPro database.
InterPro entry IPR000101
Gamma-glutamyltranspeptidase (EC) (GGT) [PUBMED:2868390] catalyzes the transfer of the gamma-glutamyl moiety of glutathione to an acceptor that may be an amino acid, a peptide or water (forming glutamate). GGT plays a key role in the gamma-glutamyl cycle, a pathway for the synthesis and degradation of glutathione and drug and xenobiotic detoxification [PUBMED:1378736]. In prokaryotes and eukaryotes, it is an enzyme that consists of two polypeptide chains, a heavy and a light subunit, processed from a single chain precursor by an autocatalytic cleavage. The active site of GGT is known to be located in the light subunit. The sequences of mammalian and bacterial GGT show a number of regions of high similarity [PUBMED:2570061]. Pseudomonas cephalosporin acylases (EC) that convert 7-beta-(4-carboxybutanamido)-cephalosporanic acid (GL-7ACA) into 7-aminocephalosporanic acid (7ACA) and glutaric acid are evolutionary related to GGT and also show some GGT activity [PUBMED:1358202]. Like GGT, these GL-7ACA acylases, are also composed of two subunits.
As an autocatalytic peptidase GGT belongs to MEROPS peptidase family T3 (gamma-glutamyltransferase family, clan PB(T)). The active site residue for members of this family and family T1 is C-terminal to the autolytic cleavage site. The type example is gamma-glutamyltransferase 1 from Escherichia coli.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||gamma-glutamyltransferase activity (GO:0003840)|
|Biological process||glutathione metabolic process (GO:0006749)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- a link to the page in the Pfam site showing information about the sequence that the graphic describes
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
Note that you can see the family page for a particular domain by clicking on the graphic. You can also choose to see all sequences which have a given architecture by clicking on the Show link in each row.
Finally, because some families can be found in a very large number of architectures, we load only the first fifty architectures by default. If you want to see more architectures, click the button at the bottom of the page to load the next set.
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In the N-terminal nucleophile aminohydrolases (Ntn hydrolases) the N-terminal residue provides two catalytic groups, nucleophile and proton donor. These enzymes use the side chain of the amino-terminal residue, incorporated in a beta-sheet, as the nucleophile in the catalytic attack at the carbonyl carbon. The nucleophile is cysteine in GAT, serine in penicillin acylase, and threonine in the proteasome. All the enzymes share an unusual fold in which the nucleophile and other catalytic groups occupy equivalent sites. This fold provides both the capacity for nucleophilic attack and the possibility of autocatalytic processing .
The clan contains the following 14 members:AAT Asparaginase_2 CBAH DUF1933 DUF3700 G_glu_transpept GATase_2 GATase_4 GATase_6 GATase_7 Penicil_amidase Peptidase_C69 Phospholip_B Proteasome
We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the UniProtKB sequence database, the NCBI sequence database, and our metagenomics sequence database. More...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
We make a range of alignments for each Pfam-A family:
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- alignment generated by searching the UniProtKB sequence database using the family HMM
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You can see the alignments as HTML or in three different sequence viewers:
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You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.
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This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.
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Curation and family details
This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.
|Seed source:||Pfam-B_878 (release 3.0)|
|Number in seed:||43|
|Number in full:||3018|
|Average length of the domain:||429.40 aa|
|Average identity of full alignment:||26 %|
|Average coverage of the sequence by the domain:||86.73 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||18|
|Download:||download the raw HMM for this family|
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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
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There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
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Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
Too many species/sequences
For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.
Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.
If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.
For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.
Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
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There is 1 interaction for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the G_glu_transpept domain has been found. There are 98 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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