Transcobalamin

TCN2
Identifiers
Aliases	TCN2, D22S676, D22S750, II, TC, TC II, TC-2, TC2, TCII, transcobalamin 2
External IDs	OMIM: 613441; MGI: 98534; GeneCards: TCN2
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	2BB5, 4ZRQ
Gene location (Human)
Chr.	Chromosome 22 (human)
End	30,627,271 bp
Gene location (Mouse)
Chr.	Chromosome 11 (mouse)
End	3,882,159 bp
RNA expression pattern
	Top expressed in
	gallbladder; ; right lung; ; upper lobe of left lung; ; human kidney; ; olfactory zone of nasal mucosa; ; right adrenal cortex; ; mucosa of ileum; ; left adrenal gland; ; left uterine tube; ; left adrenal cortex;
	Top expressed in
	parotid gland; ; vestibular membrane of cochlear duct; ; right kidney; ; submandibular gland; ; human kidney; ; Epithelium of choroid plexus; ; lacrimal gland; ; proximal tubule; ; stroma of bone marrow; ; choroid plexus of fourth ventricle;
	More reference expression data
	n/a
Gene ontology
Molecular function	metal ion binding; cobalamin binding; protein binding;
Cellular component	extracellular region; endosome; lysosomal lumen; extracellular space;
Biological process	cobalamin metabolic process; cobalt ion transport; ion transport; cobalamin transport;
	Sources:Amigo / QuickGO
Orthologs
Databases	NCBI: entry; OMA: entry
	6948
	21452
	ENSG00000185339
	ENSMUSG00000020432
	P20062
	O88968
	NM_001190420; NM_000355; NM_001184726
	NM_001130458; NM_001130459; NM_015749
	NP_000346; NP_001171655
	NP_001123930; NP_001123931; NP_056564
	Wikidata
View/Edit Human	View/Edit Mouse

Transcobalamin is a protein that in humans is encoded by the gene TCN2. Transcobalamin (also known as transcobalamin II or TCII, see Nomenclature) binds Vitamin B₁₂ (cobalamin), which enables uptake of B₁₂ from the gastrointestinal tract, transport of cobalamin in the blood, and uptake by tissues.

The complex of transcobalamin bound to B₁₂ is called holotranscobalamin or "active B12". This is the fraction of B₁₂ in the blood that is able to be taken up by cells and used for cell functioning.