Entry Name Protein digestion and absorption
Description Protein is a dietary component essential for nutritional homeostasis in humans. Normally, ingested protein undergoes a complex series of degradative processes following the action of gastric, pancreatic and small intestinal enzymes. The result of this proteolytic activity is a mixture of amino acids and small peptides. Amino acids (AAs) are transported into the enterocyte (intestinal epithelial cell) by a variety of AA transporters that are specific for cationic (basic) AA, neutral AA, and anionic (acidic) AA. Small peptides are absorbed into enterocytes by the PEPT1 transporter. Inside enterocytes peptides are hydrolyzed, and the resulting amino acids are released together with those absorbed by AA transporters into blood via multiple, basolateral, AA transporters. Hydrolysis-resistant peptides, however, are transported out of the cells by a basolateral peptide transporter that has not been identified molecularly.
Class Organismal Systems; Digestive systemBRITE hierarchy
Pathway map ko04974 Protein digestion and absorption
Other DBs Orthology K01538 FXYD2, ATP1G1; sodium/potassium-transporting ATPase subunit gamma (FXYD domain-containing ion transport regulator 2)
K01539 ATP1A; sodium/potassium-transporting ATPase subunit alpha [EC:7.2.2.13 ]
K01540 ATP1B, CD298; sodium/potassium-transporting ATPase subunit beta
K04897 KCNE3; potassium voltage-gated channel Isk-related subfamily E member 3
K04916 KCNK5, K2P5.1; potassium channel subfamily K member 5
K04926 KCNQ1, KV7.1; potassium voltage-gated channel KQT-like subfamily member 1
K04945 KCNN4, KCA3.1; potassium intermediate/small conductance calcium-activated channel subfamily N member 4
K05006 KCNJ13, KIR7.1; potassium inwardly-rectifying channel subfamily J member 13
K05334 SLC6A19; solute carrier family 6 (neurotransmitter transporter) member 19
K05612 SLC1A1, EAAT3; solute carrier family 1 (neuronal/epithelial high affinity glutamate transporter), member 1
K05616 SLC1A5; solute carrier family 1 (neutral amino acid transporter), member 5
K05849 SLC8A, NCX; solute carrier family 8 (sodium/calcium exchanger)
K06236 COL1A; collagen type I alpha
K06237 COL4A; collagen type IV alpha
K06238 COL6A; collagen type VI alpha
K06519 SLC3A2, MDU1, CD98; solute carrier family 3, member 2
K06823 COL18A; collagen type XVIII alpha
K07603 COL17A, BP180; collagen type XVII alpha
K08131 COL9A; collagen type IX alpha
K08132 COL12A; collagen type XII alpha
K08133 COL14A; collagen type XIV alpha
K08135 COL15A; collagen type XV alpha
K08187 SLC16A10; MFS transporter, MCT family, solute carrier family 16 (monocarboxylic acid transporters), member 10
K09632 CTRL; chymotrypsin-like protease [EC:3.4.21.-]
K12040 SLC9A3, NHE3; solute carrier family 9 (sodium/hydrogen exchanger), member 3
K13781 SLC7A8, LAT2; solute carrier family 7 (L-type amino acid transporter), member 8
K13867 SLC7A7; solute carrier family 7 (L-type amino acid transporter), member 7
K13868 SLC7A9_15, BAT1; solute carrier family 7 (L-type amino acid transporter), member 9/15
K14206 SLC15A1, PEPT1; solute carrier family 15 (oligopeptide transporter), member 1
K14207 SLC38A2, SNAT2; solute carrier family 38 (sodium-coupled neutral amino acid transporter), member 2
K14209 SLC36A, PAT; solute carrier family 36 (proton-coupled amino acid transporter)
K14210 SLC3A1, RBAT; solute carrier family 3 (neutral and basic amino acid transporter), member 1
K16617 COL13A; collagen type XIII alpha
K16628 COL7A; collagen type VII alpha
K16629 COL21A; collagen type XXI alpha
K16630 COL22A; collagen type XXII alpha
K19479 COL10A; collagen type X alpha
K19719 COL2A; collagen type II alpha
K19720 COL3A; collagen type III alpha
K19721 COL5AS; collagen type V/XI/XXIV/XXVII, alpha
K23455 COL8A; collagen type VIII alpha
K23619 COL28A; collagen type XXVIII alpha
K24339 COL16A; collagen type XVI alpha
K24340 COL19A; collagen type XIX alpha
K24355 COL23A; collagen type XXIII alpha
K24356 COL25A; collagen type XXV alpha
K24357 COL20A; collagen type XX alpha
K24358 COL26A, EMID2; collagen type XXVI alpha (EMI domain-containing protein 2)
Compound C05996 Branched chain fatty acid
Reference Authors Broer S
Title Amino acid transport across mammalian intestinal and renal epithelia.
Journal Reference Authors Palacin M, Nunes V, Font-Llitjos M, Jimenez-Vidal M, Fort J, Gasol E, Pineda M, Feliubadalo L, Chillaron J, Zorzano A
Title The genetics of heteromeric amino acid transporters.
Journal Reference Authors Goodman BE
Title Insights into digestion and absorption of major nutrients in humans.
Journal Reference Authors Wagner CA, Lang F, Broer S
Title Function and structure of heterodimeric amino acid transporters.
Journal Reference Authors Broer S
Title Apical transporters for neutral amino acids: physiology and pathophysiology.
Journal Reference Authors Wu G
Title Intestinal mucosal amino acid catabolism.
Journal Reference Authors Daniel H
Title Molecular and integrative physiology of intestinal peptide transport.
Journal Reference Authors Rubio-Aliaga I, Daniel H
Title Mammalian peptide transporters as targets for drug delivery.
Journal Reference Authors Bai JP
Title Distribution of brush-border membrane peptidases along the rat intestine.
Journal Reference Authors Guarner F, Malagelada JR
Title Gut flora in health and disease.
Journal Reference Authors Smith EA, Macfarlane GT
Title Dissimilatory amino Acid metabolism in human colonic bacteria.
Journal Reference Authors Schepers E, Glorieux G, Vanholder R
Title The gut: the forgotten organ in uremia?
Journal Reference Authors John H.Cummings
Title The large intestine in nutrition and disease
Journal Institut Danone
Reference Authors Heitzmann D, Warth R
Title Physiology and pathophysiology of potassium channels in gastrointestinal epithelia.
Journal Related ko00250 Alanine, aspartate and glutamate metabolism
ko00280 Valine, leucine and isoleucine degradation
