KEGG   PATHWAY: ko04973Help
Entry
ko04973                     Pathway                                
Name
Carbohydrate digestion and absorption
Description
Dietary carbohydrate in humans and omnivorous animals is a major nutrient.  The carbohydrates that we ingest vary from the lactose in milk to complex carbohydrates. These carbohydrates are digested to monosaccharides, mostly glucose, galactose and fructose, prior to absorption in the small intestine. Glucose and galactose are initially transported into the enterocyte by SGLT1 located in the apical brush border membrane and then exit through the basolateral membrane by either GLUT2 or exocytosis. In a new model of intestinal glucose absorption, transport by SGLT1 induces rapid insertion and activation of GLUT2 in the brush border membrane by a PKC betaII-dependent mechanism. Moreover, trafficking of apical GLUT2 is rapidly up-regulated by glucose and artificial sweeteners, which act through T1R2 + T1R3/alpha-gustducin to activate PLC-beta2 and PKC-beta II. Fructose is transported separately by the brush border GLUT5 and then released out of the enterocyte into the blood by GLUT2.
Class
Organismal Systems; Digestive system
BRITE hierarchy
Pathway map
Carbohydrate digestion and absorption
ko04973

All organismsOrtholog table
Disease
H01261  
Congenital glucose-galactose malabsorption (GGM)
Other DBs
Orthology
K01176  
alpha-amylase [EC:3.2.1.1]
K01229  
lactase-phlorizin hydrolase [EC:3.2.1.62 3.2.1.108]
K12047  
maltase-glucoamylase [EC:3.2.1.3 3.2.1.20]
K01203  
sucrase-isomaltase / oligo-1,6-glucosidase [EC:3.2.1.10 3.2.1.48]
K14158  
solute carrier family 5 (sodium/glucose cotransporter), member 1
K01539  
sodium/potassium-transporting ATPase subunit alpha [EC:3.6.3.9]
K01540  
sodium/potassium-transporting ATPase subunit beta
K01538  
sodium/potassium-transporting ATPase subunit gamma (FXYD domain-containing ion transport regulator 2)
K07593  
MFS transporter, SP family, solute carrier family 2 (facilitated glucose transporter), member 2
K00844  
hexokinase [EC:2.7.1.1]
K08171  
MFS transporter, OPA family, solute carrier family 37 (glycerol-6-phosphate transporter), member 4
K01084  
glucose-6-phosphatase [EC:3.1.3.9]
K08143  
MFS transporter, SP family, solute carrier family 2 (facilitated glucose/fructose transporter), member 5
K02649  
phosphoinositide-3-kinase, regulatory subunit
K00922  
phosphatidylinositol-4,5-bisphosphate 3-kinase [EC:2.7.1.153]
K04456  
RAC serine/threonine-protein kinase [EC:2.7.11.1]
K04851  
voltage-dependent calcium channel L type alpha-1D
K04625  
taste receptor type 1 member 2
K04626  
taste receptor type 1 member 3
Compound
C00011  
CO2
C00031  
D-Glucose
C00033  
Acetate
C00076  
Calcium cation
C00089  
Sucrose
C00092  
D-Glucose 6-phosphate
C00095  
D-Fructose
C00124  
D-Galactose
C00163  
Propanoate
C00165  
Diacylglycerol
C00208  
Maltose
C00238  
Potassium cation
C00243  
Lactose
C00246  
Butanoic acid
C00282  
Hydrogen
C00369  
Starch
C00707  
Xylan
C00714  
Pectin
C00760  
Cellulose
C01330  
Sodium cation
C01355  
Fructan
C01835  
Maltotriose
C02049  
Limit dextrin
C05981  
Phosphatidylinositol-3,4,5-trisphosphate
C08822  
Gum arabic
C12284  
Saccharin sodium anhydrous
C12285  
Sucralose
Reference
  Authors
Drozdowski LA, Thomson AB
  Title
Intestinal sugar transport.
  Journal
World J Gastroenterol 12:1657-70 (2006)
Reference
  Authors
Wright EM, Martin MG, Turk E
  Title
Intestinal absorption in health and disease--sugars.
  Journal
Best Pract Res Clin Gastroenterol 17:943-56 (2003)
Reference
  Authors
Kellett GL, Brot-Laroche E, Mace OJ, Leturque A
  Title
Sugar absorption in the intestine: the role of GLUT2.
  Journal
Annu Rev Nutr 28:35-54 (2008)
Reference
  Authors
Mace OJ, Lister N, Morgan E, Shepherd E, Affleck J, Helliwell P, Bronk JR, Kellett GL, Meredith D, Boyd R, Pieri M, Bailey PD, Pettcrew R, Foley D
  Title
An energy supply network of nutrient absorption coordinated by calcium and T1R taste receptors in rat small intestine.
  Journal
J Physiol 587:195-210 (2009)
Reference
  Authors
Kellett GL, Brot-Laroche E
  Title
Apical GLUT2: a major pathway of intestinal sugar absorption.
  Journal
Diabetes 54:3056-62 (2005)
Reference
  Authors
Goodman BE
  Title
Insights into digestion and absorption of major nutrients in humans.
  Journal
Adv Physiol Educ 34:44-53 (2010)
Reference
  Authors
Wright EM, Hirayama BA, Loo DF
  Title
Active sugar transport in health and disease.
  Journal
J Intern Med 261:32-43 (2007)
Reference
  Authors
Santer R, Hillebrand G, Steinmann B, Schaub J
  Title
Intestinal glucose transport: evidence for a membrane traffic-based pathway in humans.
  Journal
Gastroenterology 124:34-9 (2003)
Reference
  Authors
Stumpel F, Burcelin R, Jungermann K, Thorens B
  Title
Normal kinetics of intestinal glucose absorption in the absence of GLUT2: evidence for a transport pathway requiring glucose phosphorylation and transfer into the endoplasmic reticulum.
  Journal
Proc Natl Acad Sci U S A 98:11330-5 (2001)
Reference
  Authors
Wright EM, Loo DD, Hirayama BA, Turk E
  Title
Surprising versatility of Na+-glucose cotransporters: SLC5.
  Journal
Physiology (Bethesda) 19:370-6 (2004)
Reference
  Authors
Uldry M, Thorens B
  Title
The SLC2 family of facilitated hexose and polyol transporters.
  Journal
Pflugers Arch 447:480-9 (2004)
Reference
PMID:7555019
  Authors
Van Beers EH, Buller HA, Grand RJ, Einerhand AW, Dekker J
  Title
Intestinal brush border glycohydrolases: structure, function, and development.
  Journal
Crit Rev Biochem Mol Biol 30:197-262 (1995)
Reference
PMID:5089892
  Authors
Marsh MN
  Title
Digestive-absorptive functions of the enterocyte.
  Journal
Ann R Coll Surg Engl 48:356-68 (1971)
Reference
  Authors
Guarner F, Malagelada JR
  Title
Gut flora in health and disease.
  Journal
Lancet 361:512-9 (2003)
Reference
  Authors
Topping DL, Clifton PM
  Title
Short-chain fatty acids and human colonic function: roles of resistant starch and nonstarch polysaccharides.
  Journal
Physiol Rev 81:1031-64 (2001)
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