TCN1 (Transcobalamin I)
Vitamin B12 Binding and Transport Protein
Gene Information Card
| Symbol | TCN1 |
|---|---|
| Full Name | Transcobalamin I |
| Gene Type | Protein coding |
| Chromosomal Location | 11q12.1 |
| NCBI Gene ID | 6947 ncbi.nlm.nih.gov/gene/6947 |
| Ensembl ID | ENSG00000134827 |
| UniProt ID | P20061 |
| OMIM ID | 189905 |
| HGNC ID | 11652 |
| Aliases | TCI, HC, haptocorrin, transcobalamin-1 |
Description
The TCN1 gene encodes transcobalamin I (also known as haptocorrin), a glycoprotein that binds cobalamin (vitamin B12) in the blood and various body fluids. It is primarily produced by salivary glands, gastric mucosa, and neutrophils. TCN1 protects vitamin B12 from acid degradation in the stomach and facilitates its transport. Mutations in TCN1 can lead to vitamin B12 deficiency and related disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Transcobalamin I deficiency | Loss of functional haptocorrin reduces B12 binding capacity, leading to low serum B12 levels without megaloblastic anemia. | ClinVar, OMIM |
| Vitamin B12 deficiency (nutritional) | Reduced TCN1 expression or function may contribute to impaired B12 transport. | NCBI Gene, OMIM |
| Pancreatic cancer | TCN1 overexpression has been reported in pancreatic ductal adenocarcinoma, potentially as a biomarker. | COSMIC, literature |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Salivary gland | 12.5 | High |
| Stomach | 8.2 | Medium |
| Bone marrow | 6.7 | Medium |
| Pancreas | 4.1 | Low |
| Liver | 1.3 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 5.8 | Cervical cancer cell line |
| MCF7 | 3.2 | Breast cancer cell line |
| A549 | 2.1 | Lung cancer cell line |
| K562 | 7.4 | Leukemia cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.580C>T (p.Arg194*) | Nonsense | Rare | Loss of function; associated with transcobalamin I deficiency |
| c.1115G>A (p.Arg372His) | Missense | Rare | Reduced B12 binding affinity |
| c.1A>G (p.Met1?) | Start loss | Very rare | Complete loss of protein expression |
Mutation functional classification
Loss of Function (LOF)
Nonsense and frameshift mutations in TCN1 lead to truncated or absent haptocorrin, impairing B12 binding and transport.
Gain of Function (GOF)
No known gain-of-function mutations reported for TCN1.
Dominant Negative (DN)
No evidence of dominant-negative effects; TCN1 deficiency is typically autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Vitamin B12 (cobalamin) transport and metabolism
• Cobalamin (B12) binding and uptake
Protein Summary
Transcobalamin I (haptocorrin) is a 433-amino-acid glycoprotein that binds cobalamin with high affinity. It is secreted into saliva, gastric juice, and plasma, protecting vitamin B12 from degradation and facilitating its intestinal absorption. The protein contains a cobalamin-binding domain and is essential for normal B12 homeostasis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| VTCN1 Knockout HEK293 Cell Line | EDJ-KQ2410 | Human | 79679 | Details Get a Quote |
| TCN1 Knockout HEK293 Cell Line | EDJ-KQ11987 | Human | 6947 | Details Get a Quote |
| TCN1 Knockout HCT 116 Cell Line | EDJ-KQ40558 | Human | 6947 | Details Get a Quote |
| Vtcn1 Knockout B16-F10 Cell Line | EDJ-KZ80 | Mouse | 79679 | Details Get a Quote |
| TCN1 Knockout HeLa Cell Line | EDJ-KQ54628 | Human | 6947 | Details Get a Quote |
| VTCN1 Knockout HeLa Cell Line | EDJ-KQ57204 | Human | 79679 | Details Get a Quote |
| TCN1 Knockout A-549 Cell Line | EDJ-KQ63110 | Human | 6947 | Details Get a Quote |
| VTCN1 Knockout A-549 Cell Line | EDJ-KQ65719 | Human | 79679 | Details Get a Quote |
| VTCN1 Knockout HCT 116 Cell Line | EDJ-KQ74136 | Human | 79679 | Details Get a Quote |
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