GSTK1

GSTK1
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1YZX, 3RPN, 3RPP
Identifiers
Aliases	GSTK1, GST, GST 13-13, GST13, GST13-13, GSTK1-1, hglutathione S-transferase kappa 1
External IDs	OMIM: 602321; MGI: 1923513; HomoloGene: 41075; GeneCards: GSTK1; OMA:GSTK1 - orthologs
Gene location (Human) Chr. Chromosome 7 (human)[1] Band 7q34 Start 143,244,093 bp[1] End 143,270,854 bp[1]
Gene location (Mouse) Chr. Chromosome 6 (mouse)[2] Band 6|6 B2.1 Start 42,222,869 bp[2] End 42,227,381 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in granulocyte apex of heart mucosa of transverse colon right lobe of liver rectum monocyte right adrenal cortex right uterine tube left lobe of thyroid gland right lobe of thyroid gland Top expressed in left lobe of liver epithelium of stomach right ventricle duodenum mucous cell of stomach adrenal gland myocardium of ventricle pyloric antrum interventricular septum right kidney More reference expression data BioGPS n/a
Gene ontology Molecular function protein-disulfide reductase activity transferase activity glutathione peroxidase activity glutathione transferase activity signaling receptor binding protein binding Cellular component mitochondrial inner membrane mitochondrial matrix peroxisome extracellular exosome intracellular anatomical structure membrane mitochondrion peroxisomal matrix cytosol Biological process epithelial cell differentiation glutathione derivative biosynthetic process cellular oxidant detoxification glutathione metabolic process protein targeting to peroxisome Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 373156 76263 Ensembl ENSG00000197448 ENSMUSG00000029864 UniProt Q9Y2Q3 Q9DCM2 RefSeq (mRNA) NM_015917 NM_001143679 NM_001143680 NM_001143681 NM_029555 RefSeq (protein) NP_001137151 NP_001137152 NP_001137153 NP_057001 NP_083831 Location (UCSC) Chr 7: 143.24 – 143.27 Mb Chr 6: 42.22 – 42.23 Mb PubMed search [3] [4]
Wikidata
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Glutathione S-transferase kappa 1 (GSTK1) is an enzyme that in humans is encoded by the GSTK1 gene which is located on chromosome seven.^[5] It belongs to the superfamily of enzymes known as glutathione S-transferase (GST), which are mainly known for cellular detoxification.^[6] The GSTK1 gene consists of eight exons and seven introns and although it is a member of the GST family, its structure has been found to be similar to bacterial HCCA (2-hydroxychromene-2-carboxylate) isomerases and bacterial disulphide-bond-forming DsbA oxidoreductase. This similarity has later allowed the enzyme GSTK1 to be renamed to DsbA-L.^[7] Research has also suggested that several variations of the GSTK1 gene can be responsible for metabolic diseases and certain types of cancer.^[7]

Structure

The GSTK1 enzyme is a homodimer and, like all GSTs, it contains a TRX-like domain and a helical domain. However, the GSTK1 is substantially different in its secondary structure compared to the other GSTs. The helical domain has been observed to be placed between the βαβ and ββα motifs of the TRX-like domain, rather than the TRX-like domain and the C-terminal helical domain being connected together by a short linker of alpha-helixes as normally seen in GSTs.^[6] Also, the GSTK1 dimer employs a butterfly shape and not a V-shaped crevice like in the other classes.^[6] As for the GSTK1 gene, it is ~5 kb long, has eight exons, is located on chromosome 7q34, and includes an initiator element at the transcription start site instead of a TATA or a CCAAT box.^[5]

Function

GSTK1 has been suggested to promote adiponectin multimerization in the endoplasmic reticulum (ER),^[8] but this has been contradicted by later studies.^[9] GSTK1 can prevent ER stress and ER stress-induced adiponectin down-regulation, implying that GSTK1 assists the ER’s functions. GSTK1 is located in the ER and also in the mitochondria of hepatocytes. This indicates a potential role for GSTK1 in the interaction between the two organelles; though this is poorly understood.^[8]

The discovery of GSTK1 in the peroxisome has led to studies based on its function. It has been suggested that, similar to GSTA, GSTK1 may play a role in the buffering of acyl-CoA and xenobiotic-CoA and be involved in their binding activities. GSTK1 may also be responsible for the detoxification of lipid peroxides created in the peroxisome based on the peroxidase activity towards three substrates: tert-butyl hydroperoxide, cumene hydroperoxide, and 15-S-hydroperoxy-5,8,11,13-eicosatetraenoic acid.^[5]

Clinical significance

The amount of expression of adiponectin has been observed to be related to diseases such as insulin resistance, obesity, and type 2 diabetes. Decreased amounts of the protein indicates that there is a higher probability of receiving said diseases. Because the GSTK1 is seen to play a role in the multimerization of adiponectin, this enzyme can regulate the concentration of adiponectin and thus enhance insulin sensitivity and protect against diabetes.^[7] Also, the GSTK1 gene is unregulated when it is inflicted with oxidative stress and are over expressed in many tumors leading to difficulties during cancer chemotherapy.^[10] Moreover, GSTK1 gene expression has been seen to increase significantly in correlation to drug resistance in tumor cells such as erythroleukemia and mammary adenocarcinoma suggesting that it, along with GSTP1 and GSTA4, could be responsible for the drug resistance.^[11]

GSTK1 can also be a potential tool to help investigate cancer. Tyrosine phosphorylated proteins are responsible for many of the cell functions such as the cell’s growth, division, adhesion, and motility. These activities are also very related to cancer and thus studying this protein could allow access to information which could classify tumors for prognosis and prediction.^[12] Due to GSTK1’s C-terminal SH2 domain, tyrosine phosphorylated proteins can bind to it and allow for easier detection to which the protein can be studied.^[12]

Interactions

GSTK1 has been suggested to interact with:

• adiponectin^[8]
• Erol-Lα^[8]

References

Further reading