KEGG   PATHWAY: hsa04973Help
hsa04973                    Pathway                                

Carbohydrate digestion and absorption - Homo sapiens (human)
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.
09150 Organismal Systems; 09154 Digestive system
BRITE hierarchy
Pathway map
hsa04973  Carbohydrate digestion and absorption

Ortholog table
H01261  Congenital glucose-galactose malabsorption (GGM)
H01939  Glycogen storage disease type I
H01947  Fanconi-Bickel syndrome
D00216  Acarbose (JAN/USAN/INN)
D00625  Miglitol (JP17/USAN/INN)
D01665  Voglibose (JP17/USAN/INN)
D02381  Aspartame (NF/INN)
D08836  Acesulfame potassium (NF)
D08862  Aspartame acesulfame (NF)
D09779  Emiglitate (JAN/INN)
D10669  Sotagliflozin (USAN/INN)
Other DBs
BSID: 170720
GO: 0044245 0001951
Homo sapiens (human) [GN:hsa]
278  AMY1C; amylase, alpha 1C (salivary) [KO:K01176] [EC:]
279  AMY2A; amylase, alpha 2A (pancreatic) [KO:K01176] [EC:]
276  AMY1A; amylase, alpha 1A (salivary) [KO:K01176] [EC:]
280  AMY2B; amylase, alpha 2B (pancreatic) [KO:K01176] [EC:]
277  AMY1B; amylase, alpha 1B (salivary) [KO:K01176] [EC:]
3938  LCT; lactase [KO:K01229] [EC:]
8972  MGAM; maltase-glucoamylase [KO:K12047] [EC:]
93432  MGAM2; maltase-glucoamylase 2 (putative) [KO:K12047] [EC:]
6476  SI; sucrase-isomaltase [KO:K01203] [EC:]
6523  SLC5A1; solute carrier family 5 member 1 [KO:K14158]
476  ATP1A1; ATPase Na+/K+ transporting subunit alpha 1 [KO:K01539] [EC:]
477  ATP1A2; ATPase Na+/K+ transporting subunit alpha 2 [KO:K01539] [EC:]
478  ATP1A3; ATPase Na+/K+ transporting subunit alpha 3 [KO:K01539] [EC:]
480  ATP1A4; ATPase Na+/K+ transporting subunit alpha 4 [KO:K01539] [EC:]
23439  ATP1B4; ATPase Na+/K+ transporting family member beta 4 [KO:K01540]
481  ATP1B1; ATPase Na+/K+ transporting subunit beta 1 [KO:K01540]
482  ATP1B2; ATPase Na+/K+ transporting subunit beta 2 [KO:K01540]
483  ATP1B3; ATPase Na+/K+ transporting subunit beta 3 [KO:K01540]
486  FXYD2; FXYD domain containing ion transport regulator 2 [KO:K01538]
6514  SLC2A2; solute carrier family 2 member 2 [KO:K07593]
3101  HK3; hexokinase 3 [KO:K00844] [EC:]
3098  HK1; hexokinase 1 [KO:K00844] [EC:]
3099  HK2; hexokinase 2 [KO:K00844] [EC:]
80201  HKDC1; hexokinase domain containing 1 [KO:K00844] [EC:]
2542  SLC37A4; solute carrier family 37 member 4 [KO:K08171]
2538  G6PC; glucose-6-phosphatase catalytic subunit [KO:K01084] [EC:]
57818  G6PC2; glucose-6-phosphatase catalytic subunit 2 [KO:K01084] [EC:]
92579  G6PC3; glucose-6-phosphatase catalytic subunit 3 [KO:K01084] [EC:]
6518  SLC2A5; solute carrier family 2 member 5 [KO:K08143]
5295  PIK3R1; phosphoinositide-3-kinase regulatory subunit 1 [KO:K02649]
5296  PIK3R2; phosphoinositide-3-kinase regulatory subunit 2 [KO:K02649]
8503  PIK3R3; phosphoinositide-3-kinase regulatory subunit 3 [KO:K02649]
5290  PIK3CA; phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha [KO:K00922] [EC:]
5293  PIK3CD; phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit delta [KO:K00922] [EC:]
5291  PIK3CB; phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit beta [KO:K00922] [EC:]
207  AKT1; AKT serine/threonine kinase 1 [KO:K04456] [EC:]
208  AKT2; AKT serine/threonine kinase 2 [KO:K04456] [EC:]
10000  AKT3; AKT serine/threonine kinase 3 [KO:K04456] [EC:]
776  CACNA1D; calcium voltage-gated channel subunit alpha1 D [KO:K04851]
5579  PRKCB; protein kinase C beta [KO:K19662] [EC:]
80834  TAS1R2; taste 1 receptor member 2 [KO:K04625]
83756  TAS1R3; taste 1 receptor member 3 [KO:K04626]
346562  GNAT3; G protein subunit alpha transducin 3 [KO:K19729]
5330  PLCB2; phospholipase C beta 2 [KO:K05858] [EC:]
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
Drozdowski LA, Thomson AB
Intestinal sugar transport.
World J Gastroenterol 12:1657-70 (2006)
Wright EM, Martin MG, Turk E
Intestinal absorption in health and disease--sugars.
Best Pract Res Clin Gastroenterol 17:943-56 (2003)
Kellett GL, Brot-Laroche E, Mace OJ, Leturque A
Sugar absorption in the intestine: the role of GLUT2.
Annu Rev Nutr 28:35-54 (2008)
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
An energy supply network of nutrient absorption coordinated by calcium and T1R taste receptors in rat small intestine.
J Physiol 587:195-210 (2009)
Kellett GL, Brot-Laroche E
Apical GLUT2: a major pathway of intestinal sugar absorption.
Diabetes 54:3056-62 (2005)
Goodman BE
Insights into digestion and absorption of major nutrients in humans.
Adv Physiol Educ 34:44-53 (2010)
Wright EM, Hirayama BA, Loo DF
Active sugar transport in health and disease.
J Intern Med 261:32-43 (2007)
Santer R, Hillebrand G, Steinmann B, Schaub J
Intestinal glucose transport: evidence for a membrane traffic-based pathway in humans.
Gastroenterology 124:34-9 (2003)
Stumpel F, Burcelin R, Jungermann K, Thorens B
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.
Proc Natl Acad Sci U S A 98:11330-5 (2001)
Wright EM, Loo DD, Hirayama BA, Turk E
Surprising versatility of Na+-glucose cotransporters: SLC5.
Physiology (Bethesda) 19:370-6 (2004)
Uldry M, Thorens B
The SLC2 family of facilitated hexose and polyol transporters.
Pflugers Arch 447:480-9 (2004)
Van Beers EH, Buller HA, Grand RJ, Einerhand AW, Dekker J
Intestinal brush border glycohydrolases: structure, function, and development.
Crit Rev Biochem Mol Biol 30:197-262 (1995)
Marsh MN
Digestive-absorptive functions of the enterocyte.
Ann R Coll Surg Engl 48:356-68 (1971)
Guarner F, Malagelada JR
Gut flora in health and disease.
Lancet 361:512-9 (2003)
Topping DL, Clifton PM
Short-chain fatty acids and human colonic function: roles of resistant starch and nonstarch polysaccharides.
Physiol Rev 81:1031-64 (2001)
KO pathway

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