ID:STK11_HUMAN DESCRIPTION: RecName: Full=Serine/threonine-protein kinase STK11; EC=2.7.11.1; AltName: Full=Liver kinase B1; Short=LKB1; Short=hLKB1; AltName: Full=Renal carcinoma antigen NY-REN-19; FUNCTION: Tumor suppressor serine/threonine-protein kinase that controls the activity of AMP-activated protein kinase (AMPK) family members, thereby playing a role in various processes such as cell metabolism, cell polarity, apoptosis and DNA damage response. Acts by phosphorylating the T-loop of AMPK family proteins, leading to promote their activity: phosphorylates PRKAA1, PRKAA2, BRSK1, BRSK2, MARK1, MARK2, MARK3, MARK4, NUAK1, NUAK2, SIK1, SIK2, SIK3 and SNRK but not MELK. Also phosphorylates non-AMPK family proteins such as STRADA and possibly p53/TP53. Acts as a key upstream regulator of AMPK by mediating phosphorylation and activation of AMPK catalytic subunits PRKAA1 and PRKAA2: it thereby regulates inhibition of signaling pathways that promote cell growth and proliferation when energy levels are low, glucose homeostasis in liver, activation of autophagy when cells undergo nutrient deprivation, B-cell differentiation in the germinal center in response to DNA damage. Also acts as a regulator of cellular polarity by remodeling the actin cytoskeleton. Required for cortical neurons polarization by mediating phosphorylation and activation of BRSK1 and BRSK2, leading to axon initiation and specification. Involved in DNA damage response: interacts with p53/TP53 and recruited to the CDKN1A/WAF1 promoter to participate in transcription activation. Able to phosphorylate p53/TP53; the relevance of such result in vivo is however unclear and phosphorylation may be indirect and mediated by downstream STK11/LKB1 kinase NUAK1 Also acts as a mediator p53/TP53-dependent apoptosis via interaction with p53/TP53: translocates to mitochondrion during apoptosis and regulates p53/TP53-dependent apoptosis pathways. CATALYTIC ACTIVITY: ATP + a protein = ADP + a phosphoprotein. COFACTOR: Magnesium or Manganese. ENZYME REGULATION: Activated by forming a complex with STRAD (STRADA or STRADB) and CAB39/MO25 (CAB39/MO25alpha or CAB39L/MO25beta): STRADA (or STRADB)-binding promotes a conformational change of STK11/LKB1 in an active conformation, which is stabilized by CAB39/MO25alpha (or CAB39L/MO25beta) interacting with the STK11/LKB1 activation loop. SUBUNIT: Catalytic component of a trimeric complex composed of STK11/LKB1, STRAD (STRADA or STRADB) and CAB39/MO25 (CAB39/MO25alpha or CAB39L/MO25beta): the complex tethers STK11/LKB1 in the cytoplasm and stimulates its catalytic activity. Found in a ternary complex composed of SMAD4, STK11/LKB1 and STK11IP. Interacts with p53/TP53, SMAD4, STK11IP and WDR6. INTERACTION: Q9Y376:CAB39; NbExp=4; IntAct=EBI-306838, EBI-306905; Q96L34:MARK4; NbExp=2; IntAct=EBI-306838, EBI-302319; Q7RTN6:STRADA; NbExp=9; IntAct=EBI-306838, EBI-1109114; Q9C0K7:STRADB; NbExp=6; IntAct=EBI-306838, EBI-306893; Q8NFZ5:TNIP2; NbExp=5; IntAct=EBI-306838, EBI-359372; Q9NNW5:WDR6; NbExp=3; IntAct=EBI-306838, EBI-1568315; SUBCELLULAR LOCATION: Nucleus. Cytoplasm. Membrane (By similarity). Mitochondrion. Note=A small fraction localizes at membranes (By similarity). Relocates to the cytoplasm when bound to STRAD (STRADA or STRADB) and CAB39/MO25 (CAB39/MO25alpha or CAB39L/MO25beta). Translocates to mitochondrion during apoptosis. TISSUE SPECIFICITY: Ubiquitously expressed. Strongest expression in testis and fetal liver. PTM: Phosphorylated by ATM at Thr-363 following ionizing radiations (IR). Phosphorylation at Ser-428 by RPS6KA1 and/or some PKA is required to inhibit cell growth. Phosphorylation at Ser-428 is also required during neuronal polarization to mediate phosphorylation of BRSK1 and BRSK2 (By similarity). DISEASE: Defects in STK11 are a cause of Peutz-Jeghers syndrome (PJS) [MIM:175200]. PJS is a rare hereditary disease in which there is predisposition to benign and malignant tumors of many organ systems. PJS is an autosomal dominant disorder characterized by melanocytic macules of the lips, multiple gastrointestinal hamartomatous polyps and an increased risk for various neoplasms, including gastrointestinal cancer. DISEASE: Defects in STK11 have been associated with testicular germ cell tumor (TGCT) [MIM:273300]. A common solid malignancy in males. Germ cell tumors of the testis constitute 95% of all testicular neoplasms. DISEASE: Note=Defects in STK11 are associated with some sporadic cancers, especially lung cancers. Frequently mutated and inactivated in non-small cell lung cancer (NSCLC). Defects promote lung cancerigenesis process, especially lung cancer progression and metastasis. Confers lung adenocarcinoma the ability to trans- differentiate into squamous cell carcinoma. Also able to promotes lung cancer metastasis, via both cancer-cell autonomous and non- cancer-cell autonomous mechanisms. SIMILARITY: Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. LKB1 subfamily. SIMILARITY: Contains 1 protein kinase domain. WEB RESOURCE: Name=Atlas of Genetics and Cytogenetics in Oncology and Haematology; URL="http://atlasgeneticsoncology.org/Genes/STK11ID292.html"; WEB RESOURCE: Name=GeneReviews; URL="http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/gene/STK11"; WEB RESOURCE: Name=Wikipedia; Note=PJS entry; URL="http://en.wikipedia.org/wiki/PJS";
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on Q15831
Front
Top
Side
The pictures above may be empty if there is no ModBase structure for the protein. The ModBase structure frequently covers just a fragment of the protein. You may be asked to log onto ModBase the first time you click on the pictures. It is simplest after logging in to just click on the picture again to get to the specific info on that model.
Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
US Server
Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
