AAT Bioquest

Type I Collagen

Type I collagen (Col-I), a fibrillary type collagen, is the most abundant collagen in the human body accounting for 90% of all collagen. It is the major protein component of the bone extracellular matrix and is commonly present in tissues where increased tensile strength is required, such as ligaments, tendons, menisci, skin, blood vessels, intervertebral discs, and cornea. The dominant isoform of type 1 collagen is a heterotrimer (i.e., a triple-helix structure) consisting of two pro-alpha1(I) chains and a pro-alpha2(I) chain. However, homotrimers of three pro-alpha1(I) chains, known to play a key role in wound healing, have been documented in fetal tissues, tumors, and some fibrotic lesions. In humans, pro-alpha1(I) and pro-alpha2(I) chains are transcribed and processed from COL1A1 and COL1A2 genes, respectively. The majority of type I collagen mutations result in bone and connective tissue disorders, in particular, osteogenesis imperfect types I-IV (brittle bone disease), Ehlers-Danlos syndrome classical type, Ehlers-Danlos syndrome type VIIA, idiopathic osteoporosis, and Caffey disease. Biomarkers for type I collagen are divided into two categories, degradation, and synthesis biomarkers. Col-I degradation biomarkers include Col-I neoepitope (C1M), C-terminal telopeptide of Col-I (CTX-I), and Col-I-derived crosslinked carboxy-terminal telopeptide (ICTP). Col-I synthesis biomarkers include carboxy-terminal propeptides of pro Col-I (PICP) and amino-terminal propeptides of pro Col-I (PINP).

Type I collagen has been visualized using a variety of techniques. Scanning and transmission electron microscopy provide high-resolution visualization of individual collagen fibers, but, is labor-intensive and expensive to perform. Western blot, IHC, IF and ELISA using type I collagen specific antibodies are more cost-effective alternatives, providing similar levels of sensitivity and are easily reproducible. In addition, single-cell RNA-sequencing analysis has been used to identify collagen I-producing cells and lineages in bone and bone marrow fractions.

Table 1. Type I collagen at-a-glance.

Chain Composition
Cell Types
Database Links
Type I collagenTwo pro-alpha1(I) chains, One pro-alpha2(I) chainFibroblasts
Gene ID: 1277 (type 1 collagen &alpha1), 1278 (type 1 collagen, &alpha2)
UniPort: P02452 (type 1 collagen, &alpha1), P08123 (type 1 collagen, &alpha2)
OMIM: 120150 (type 1 collagen, &alpha1), 120160 (type 1 collagen, &alpha2)

Table 2. Collagen antibodies.

Application Dilutions
Unit Size
Cat No.
Collagen I AntibodyPolyclonalRabbitHuman, Mouse, RatUnconjugatedIHC: 1:50∼1-100
IF: 1:100∼1-500
ELISA: 1:5000
50 µg8C0154
Collagen I α2 (Cleaved-Gly1102) AntibodyPolyclonalRabbitHumanUnconjugatedWB: 1:500∼1:1000
IHC: 1:50∼1-100
IF: 1:100∼1:500
ELISA: 1:20000
50 µg8C12195
Collagen I α2 AntibodyPolyclonalRabbitHumanUnconjugatedWB: 1:500∼1:1000
ELISA: 1:10000
50 µg8L0220



  1. Ricard-Blum S. (2011). The collagen family. Cold Spring Harbor perspectives in biology, 3(1), a004978. https://doi.org/10.1101/cshperspect.a004978

Original created on March 15, 2022, last updated on March 15, 2022
Tagged under: Collagen I, Col-I, Bone extracellular matrix, Osteogenesis imperfecta, Ehlers-Danlos syndrome, Anti-Collagen I, Collagen I antibodies, Pro-alpha1(I) chain, Pro-alpha2(I) chain