Biomaterial Database

Evidence for intestinal origin of transcobalamin II during vitamin B12 absorption. 1978

I Chanarin, and M Muir, and A Hughes, and A V Hoffbrand

The plasma binding of newly absorbed, radioactively labelled vitamin B12 was studied during a urinary excretion (Schilling) test. Vitamin B12, after being absorbed from the gut, enters blood attached to transcobalamin II, which seems to be derived from the ileal enterocyte. The absorbed B12 re-enters the blood stream after the transcobalamin II-B12 complex is cleared by the liver and it is then excreted into the urine during the Schilling test.

UI	MeSH Term	Description	Entries
D007408	Intestinal Absorption	Uptake of substances through the lining of the INTESTINES.	Absorption, Intestinal
D007413	Intestinal Mucosa	Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.	Intestinal Epithelium,Intestinal Glands,Epithelium, Intestinal,Gland, Intestinal,Glands, Intestinal,Intestinal Gland,Mucosa, Intestinal
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D001798	Blood Proteins	Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.	Blood Protein,Plasma Protein,Plasma Proteins,Serum Protein,Serum Proteins,Protein, Blood,Protein, Plasma,Protein, Serum,Proteins, Blood,Proteins, Plasma,Proteins, Serum
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000368	Aged	A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available.	Elderly
D012546	Schilling Test	A diagnostic test in which vitamin B12 is tagged with radioactive cobalt, taken orally, and gastrointestinal absorption is determined via measurement of the amount of radioactivity in a 24-hour urine collection.	Test, Schilling
D014155	Transcobalamins	A group of carrier proteins which bind with VITAMIN B12 in the BLOOD and aid in its transport. Transcobalamin I migrates electrophoretically as a beta-globulin, while transcobalamins II and III migrate as alpha-globulins.	Cobalamin-Binding Protein,Transcobalamin,Transcobalamin II,Vitamin B 12-Binding Protein,Vitamin B 12-Binding Proteins,Vitamin B12-Binding Protein,Cobalamin-Binding Proteins,Cobalophilin,Haptocorrin,Holo-Transcobalamin II,R-Binder,Transcobalamin (I),Transcobalamin I,Transcobalamin III,Vitamin B 12 Binder,Vitamin B12-Binding Proteins,B12-Binding Protein, Vitamin,Cobalamin Binding Protein,Cobalamin Binding Proteins,Holo Transcobalamin II,Protein, Cobalamin-Binding,Protein, Vitamin B12-Binding,Proteins, Cobalamin-Binding,Proteins, Vitamin B12-Binding,R Binder,Vitamin B 12 Binding Protein,Vitamin B 12 Binding Proteins,Vitamin B12 Binding Protein,Vitamin B12 Binding Proteins
D014805	Vitamin B 12	A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.	Cobalamin,Cyanocobalamin,Cobalamins,Eritron,Vitamin B12,B 12, Vitamin,B12, Vitamin