CSN2: Beta-Casein Gene
Key milk protein gene with roles in nutrition, allergy, and potential cancer association
Gene Information Card
| Symbol | CSN2 |
|---|---|
| Full Name | Casein Beta |
| Gene Type | protein-coding |
| Chromosomal Location | 4q13.3 |
| NCBI Gene ID | 1447 ncbi.nlm.nih.gov/gene/1447 |
| Ensembl ID | ENSG00000135222 |
| UniProt ID | P05814 |
| OMIM ID | 115460 |
| HGNC ID | 2447 |
| Aliases | CASB, beta-casein |
Description
The CSN2 gene encodes beta-casein, a major milk protein that constitutes approximately 30% of total casein in bovine and human milk. Beta-casein is a phosphoprotein that binds calcium and is essential for micelle formation, providing amino acids and minerals to neonates. Variants such as A1 and A2 beta-casein differ by a single amino acid substitution (Pro67His) and have been studied for differential effects on digestion and health. The gene is expressed primarily in mammary gland during lactation.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Milk allergy (beta-casein specific) | IgE-mediated hypersensitivity to beta-casein epitopes | ClinVar: Pathogenic variants associated with allergy; NCBI GeneReviews |
| Type 1 diabetes (potential association) | A1 beta-casein variant may trigger immune cross-reactivity with pancreatic beta-cells | Epidemiological studies; not confirmed by OMIM |
| Autism spectrum disorder (speculative) | Opioid peptides from beta-casein (beta-casomorphin-7) hypothesized to affect neurodevelopment | Limited evidence; not listed in OMIM or ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Mammary gland | High (nTPM ~5000) | High |
| Breast | Moderate (nTPM ~200) | Moderate |
| Other tissues | Not detected | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| MCF-7 (breast cancer) | Low | Expression may be aberrant in some breast cancer lines |
| MDA-MB-231 | Not detected | Triple-negative breast cancer line |
| HEK293 | Not detected | Non-mammary origin |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.200C>A (p.Pro67His) | Missense | Common in A1 allele (frequency ~0.3-0.5 in European cattle) | Alters digestion; associated with beta-casomorphin-7 release |
| c.200C>T (p.Pro67Leu) | Missense | Rare | Unknown functional effect |
| c.67G>A (p.Glu23Lys) | Missense | Rare | Reported in ClinVar as variant of uncertain significance |
Mutation functional classification
Loss of Function (LOF)
No well-characterized loss-of-function mutations reported in humans; null alleles in cattle lead to reduced milk beta-casein content.
Gain of Function (GOF)
Not described for CSN2.
Dominant Negative (DN)
Not described for CSN2.
View complete mutation data：
Gene Ontology (GO)
Pathways
• KEGG: hsa04978 - Mineral absorption
• Reactome: R-HSA-382551 - Transport of small molecules
• Reactome: R-HSA-8957275 - Post-translational protein phosphorylation
Protein Summary
Beta-casein (UniProt P05814) is a 224-amino-acid phosphoprotein with a signal peptide (residues 1-15). It is highly phosphorylated at serine residues, enabling calcium binding and micelle formation. The protein is a precursor to bioactive peptides, including beta-casomorphin-7, which has opioid activity. Variant A1 (Pro67His) is more readily cleaved by digestive enzymes to release beta-casomorphin-7 compared to A2. The protein is secreted into milk and is a major nutritional component.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CSN2 Knockout HEK293 Cell Line | EDJ-KQ4364 | Human | 1447 | Details Get a Quote |
| CSN2 Knockout HeLa Cell Line | EDJ-KQ53009 | Human | 1447 | Details Get a Quote |
| CSN2 Knockout A-549 Cell Line | EDJ-KQ61475 | Human | 1447 | Details Get a Quote |
| CSN2 Knockout HCT 116 Cell Line | EDJ-KQ69972 | Human | 1447 | Details Get a Quote |
