Entry Name Carbohydrate digestion and absorption - Equus caballus (horse)
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 systemBRITE hierarchy
Pathway map ecb04973 Carbohydrate digestion and absorption
Ortholog table Other DBs Organism Equus caballus (horse) [GN:
ecb ]
Gene 100062895 ATP1B3; sodium/potassium-transporting ATPase subunit beta-3 [KO:K01540 ]
100033968 ATP1B1; sodium/potassium-transporting ATPase subunit beta-1 [KO:K01540 ]
100073014 ATP1B2; sodium/potassium-transporting ATPase subunit beta-2 isoform X1 [KO:K01540 ]
100629801 FXYD2; sodium/potassium-transporting ATPase subunit gamma isoform X1 [KO:K01538 ]
100033974 SLC2A2; solute carrier family 2, facilitated glucose transporter member 2 [KO:K07593 ]
100063238 SLC37A4; glucose-6-phosphate exchanger SLC37A4 isoform X1 [KO:K08171 ]
100033971 SLC2A5; solute carrier family 2, facilitated glucose transporter member 5 [KO:K08143 ]
100052122 phosphatidylinositol 3-kinase regulatory subunit gamma isoform X1 [KO:K02649 ]
100050227 PIK3R1; phosphatidylinositol 3-kinase regulatory subunit alpha isoform X3 [KO:K02649 ]
100146348 PIK3R2; phosphatidylinositol 3-kinase regulatory subunit beta [KO:K02649 ]
100051623 PIK3CD; phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit delta isoform isoform X1 [KO:K00922 ] [EC:2.7.1.153 ]
100058141 PIK3CA; phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform isoform X1 [KO:K00922 ] [EC:2.7.1.153 ]
100051753 PIK3CB; phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit beta isoform [KO:K00922 ] [EC:2.7.1.153 ]
100051186 CACNA1D; voltage-dependent L-type calcium channel subunit alpha-1D isoform X1 [KO:K04851 ]
100049917 GNAT3; guanine nucleotide-binding protein G(t) subunit alpha-3 [KO:K19729 ]
100057315 PLCB2; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-2 isoform X1 [KO:K05858 ] [EC:3.1.4.11 ]
100051558 PLCB1; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-1 isoform X1 [KO:K05858 ] [EC:3.1.4.11 ]
100051485 PLCB4; 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase beta-4 isoform X1 [KO:K05858 ] [EC:3.1.4.11 ]
Compound C05981 Phosphatidylinositol-3,4,5-trisphosphate
C12284 Saccharin sodium anhydrous
Reference Authors Drozdowski LA, Thomson AB
Title Intestinal sugar transport.
Journal Reference Authors Wright EM, Martin MG, Turk E
Title Intestinal absorption in health and disease--sugars.
Journal Reference Authors Kellett GL, Brot-Laroche E, Mace OJ, Leturque A
Title Sugar absorption in the intestine: the role of GLUT2.
Journal 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 Reference Authors Kellett GL, Brot-Laroche E
Title Apical GLUT2: a major pathway of intestinal sugar absorption.
Journal Reference Authors Goodman BE
Title Insights into digestion and absorption of major nutrients in humans.
Journal Reference Authors Wright EM, Hirayama BA, Loo DF
Title Active sugar transport in health and disease.
Journal Reference Authors Santer R, Hillebrand G, Steinmann B, Schaub J
Title Intestinal glucose transport: evidence for a membrane traffic-based pathway in humans.
Journal 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 Reference Authors Wright EM, Loo DD, Hirayama BA, Turk E
Title Surprising versatility of Na+-glucose cotransporters: SLC5.
Journal Reference Authors Uldry M, Thorens B
Title The SLC2 family of facilitated hexose and polyol transporters.
Journal Reference Authors Van Beers EH, Buller HA, Grand RJ, Einerhand AW, Dekker J
Title Intestinal brush border glycohydrolases: structure, function, and development.
Journal Reference 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 Reference Authors Topping DL, Clifton PM
Title Short-chain fatty acids and human colonic function: roles of resistant starch and nonstarch polysaccharides.
Journal Related KO pathway LinkDB All DBs
