collagen type IX alpha 1
The COL9A1 gene provides instructions for making part of a large molecule called type IX collagen. Collagens are a family of proteins that strengthen and support connective tissues, such as skin, bone, cartilage, tendons, and ligaments. In particular, type IX collagen is an important component of cartilage, which is a tough, flexible tissue that makes up much of the skeleton during early development. Most cartilage is later converted to bone, except for the cartilage that continues to cover and protect the ends of bones and is present in the nose and external ears.
Type IX collagen is made up of three proteins that are produced from three distinct genes: one α1(IX) chain, which is produced from the COL9A1 gene, one α2(IX) chain, which is produced from the COL9A2 gene, and one α3(IX) chain, which is produced from the COL9A3 gene. Type IX collagen is more flexible than other types of collagen molecules and is closely associated with type II collagen. Researchers believe that the flexible nature of type IX collagen allows it to act as a bridge that connects type II collagen with other cartilage components. Studies have shown that type IX collagen also interacts with the proteins produced from the MATN3 and COMP genes.
At least one mutation in the COL9A1 gene has been found to cause dominant multiple epiphyseal dysplasia, a disorder of cartilage and bone development that primarily affects the ends of the long bones in the arms and legs (epiphyses). The identified mutation, called a splice-site mutation, involves the addition of one DNA building block (nucleotide) near an area of the gene called exon 8 (written as 1-bp ins, IVS8, T, +3). This mutation disrupts the way the gene's instructions are used to make the α1(IX) chain, resulting in a deletion of several protein building blocks (amino acids). It is not known how this mutation in COL9A1 causes the signs and symptoms of dominant multiple epiphyseal dysplasia.
Genetics Home Reference provides information about Stickler syndrome.
- alpha 1 type IX collagen
- cartilage-specific short collagen
- collagen IX, alpha-1 polypeptide
- collagen, type IX, alpha 1