KEGG   PATHWAY: map04973Help
Entry
map04973                    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
map04973

All organismsOrtholog table
Disease
H01261  
Congenital glucose-galactose malabsorption (GGM)
Other DBs
Reference
  Authors
Drozdowski LA, Thomson AB
  Title
Intestinal sugar transport.
  Journal
World J Gastroenterol 12:1657-70 (2006)
DOI:10.3748/wjg.v12.i11.1657
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)
DOI:10.1016/S1521-6918(03)00107-0
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)
DOI:10.1146/annurev.nutr.28.061807.155518
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)
DOI:10.1113/jphysiol.2008.159616
Reference
  Authors
Kellett GL, Brot-Laroche E
  Title
Apical GLUT2: a major pathway of intestinal sugar absorption.
  Journal
Diabetes 54:3056-62 (2005)
DOI:10.2337/diabetes.54.10.3056
Reference
  Authors
Goodman BE
  Title
Insights into digestion and absorption of major nutrients in humans.
  Journal
Adv Physiol Educ 34:44-53 (2010)
DOI:10.1152/advan.00094.2009
Reference
  Authors
Wright EM, Hirayama BA, Loo DF
  Title
Active sugar transport in health and disease.
  Journal
J Intern Med 261:32-43 (2007)
DOI:10.1111/j.1365-2796.2006.01746.x
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)
DOI:10.1053/gast.2003.50009
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)
DOI:10.1073/pnas.211357698
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)
DOI:10.1152/physiol.00026.2004
Reference
  Authors
Uldry M, Thorens B
  Title
The SLC2 family of facilitated hexose and polyol transporters.
  Journal
Pflugers Arch 447:480-9 (2004)
DOI:10.1007/s00424-003-1085-0
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)
DOI:10.3109/10409239509085143
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)
DOI:10.1016/S0140-6736(03)12489-0
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)
KO pathway
 

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