COL1A1: The Alpha-1 Chain of Type I Collagen — From Bone Strength to Disease
A comprehensive biomedical overview of the COL1A1 gene, its protein product, tissue expression, associated diseases, and mutation landscape.
Gene Information Card
| Symbol | COL1A1 |
|---|---|
| Full Name | Collagen Type I Alpha 1 Chain |
| Gene Type | Protein coding |
| Chromosomal Location | 17q21.33 |
| NCBI Gene ID | 1277 ncbi.nlm.nih.gov/gene/1277 |
| Ensembl ID | ENSG00000108821 |
| UniProt ID | P02452 |
| OMIM ID | 120150 |
| HGNC ID | 2197 |
| Aliases | OI4, EDSC, CAF, COL1A1/COL1A2 |
Description
The COL1A1 gene encodes the pro-alpha1(I) chain of type I collagen, the most abundant protein in the human body and a major structural component of bone, skin, tendons, ligaments, and cornea. It is synthesized as a precursor molecule that undergoes extensive post-translational modification, including hydroxylation and glycosylation, before assembling into a triple-helical structure with another pro-alpha1(I) chain and one pro-alpha2(I) chain (encoded by COL1A2). This triple helix is crucial for the tensile strength and structural integrity of connective tissues. Mutations in COL1A1 can lead to a spectrum of diseases, most notably osteogenesis imperfecta (brittle bone disease), but also certain types of Ehlers-Danlos syndrome and other connective tissue disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Osteogenesis Imperfecta (OI) | Most OI cases are caused by dominant-negative mutations in COL1A1 or COL1A2, leading to the production of structurally abnormal pro-alpha1(I) chains that disrupt the normal collagen triple helix formation. This results in reduced or abnormal type I collagen in bone, causing bone fragility and deformities. | ClinVar, OMIM |
| Ehlers-Danlos Syndrome, Arthrochalasia Type (EDSARTH) | Specific mutations in COL1A1, often leading to exon skipping, result in the production of a shortened pro-alpha1(I) chain that interferes with the N-terminal processing of the collagen molecule. This disrupts the normal assembly of collagen fibrils, leading to joint hypermobility, skin hyperextensibility, and tissue fragility. | ClinVar, OMIM |
| Caffey Disease (Infantile Cortical Hyperostosis) | A specific missense mutation (p.Arg836Cys) in COL1A1 is associated with this rare, self-limiting inflammatory disease of infancy. The mutation is thought to alter the collagen structure, triggering an inflammatory response in the periosteum, leading to bone swelling and hyperostosis. | OMIM, PubMed |
| Osteoporosis | Polymorphisms and certain regulatory variants in COL1A1, particularly in the Sp1 binding site, have been associated with reduced bone mineral density and an increased risk of osteoporosis and osteoporotic fractures. These variants may affect the ratio of COL1A1 to COL1A2 transcripts, influencing collagen structure and bone strength. | NCBI, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Bone | High | Major site of type I collagen production by osteoblasts. |
| Skin | High | Key component of the dermal extracellular matrix. |
| Tendon | High | Provides tensile strength to tendons. |
| Ligament | High | Structural component of ligaments. |
| Cornea | High | Contributes to the transparency and structural integrity of the cornea. |
| Lung | Medium | Present in the extracellular matrix of lung tissue. |
| Artery | Medium | Found in the vascular wall. |
| Smooth Muscle | Low | Expressed in the extracellular matrix surrounding smooth muscle cells. |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Osteoblasts | High | Primary cells responsible for bone matrix synthesis. |
| Fibroblasts | High | Major producers of collagen in connective tissues. |
| Chondrocytes | Medium | Produce type I collagen in certain cartilaginous tissues. |
| Hepatic Stellate Cells | Medium | Activated cells produce collagen during liver fibrosis. |
| Mesangial Cells | Low | Produce collagen in the kidney glomerulus. |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| p.Glycine substitutions (e.g., p.Gly382Ser) | Missense | Common in OI | Disrupts the Gly-X-Y repeat pattern of the collagen triple helix, leading to a kink or destabilization of the molecule. |
| Splice-site mutations (e.g., c.IVS14+1G>A) | Splice site | Associated with OI and EDS | Can lead to exon skipping or intron retention, resulting in an abnormal mRNA and a truncated or elongated protein. |
| Nonsense mutations (e.g., p.Arg433*) | Nonsense | Cause haploinsufficiency in OI type I | Introduces a premature stop codon, leading to mRNA degradation via nonsense-mediated decay and reduced production of normal collagen. |
| p.Arg836Cys | Missense | Specific to Caffey disease | Alters the structure of the C-terminal propeptide, potentially affecting collagen assembly and triggering an inflammatory response. |
Mutation functional classification
Loss of Function (LOF)
Loss-of-function mutations, such as nonsense or frameshift mutations, lead to haploinsufficiency, where the single functional allele cannot produce enough normal collagen. This is the primary mechanism in the milder, non-deforming form of Osteogenesis Imperfecta (type I).
Gain of Function (GOF)
While not a classic gain-of-function, the p.Arg836Cys mutation in Caffey disease is considered a gain-of-function or neomorphic mutation, as it confers a new, pathological inflammatory phenotype not seen with other COL1A1 mutations.
Dominant Negative (DN)
The most common mechanism for severe OI (types II-IV). Missense mutations, particularly glycine substitutions, produce an abnormal pro-alpha1(I) chain that incorporates into the triple helix, acting as a dominant-negative and disrupting the function of the normal chains produced by the wild-type allele.
View complete mutation data：
Gene Ontology (GO)
| • extracellular matrix structural constituent | • platelet-derived growth factor binding |
| • integrin binding | • heparin binding |
| • protein binding | • identical protein binding |
| • extracellular matrix organization | • collagen fibril organization |
| • skeletal system development | • osteoblast differentiation |
| • response to wounding | • blood coagulation |
Pathways
• Collagen biosynthesis and modifying enzymes
• Assembly of collagen fibrils and other multimeric structures
• Degradation of the extracellular matrix
• Integrin signaling pathway
• Focal adhesion
• PI3K-Akt signaling pathway
• Protein digestion and absorption
Protein Summary
The COL1A1 gene encodes the pro-alpha1(I) chain, a key component of type I collagen. The protein is synthesized as a preproprotein, which is then processed to form the mature pro-alpha1(I) chain. Two pro-alpha1(I) chains and one pro-alpha2(I) chain assemble to form a procollagen triple helix. This trimer is secreted from the cell, and its N- and C-terminal propeptides are cleaved to form the mature collagen fibril. The mature type I collagen is a major structural protein, providing tensile strength to bone, skin, tendons, and other connective tissues. Mutations in this gene can lead to a variety of skeletal and connective tissue disorders.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| COL1A1 Knockout HEK293 Cell Line | EDJ-KQ768 | Human | 1277 | Details Get a Quote |
| COL1A1 Knockout A-549 Cell Line | EDJ-KQ19464 | Human | 1277 | Details Get a Quote |
| COL1A1 Knockout HCT 116 Cell Line | EDJ-KQ19465 | Human | 1277 | Details Get a Quote |
| COL1A1 Knockout HeLa Cell Line | EDJ-KQ19466 | Human | 1277 | Details Get a Quote |
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