Fibrous proteins are proteins that tend to be insoluble and strong and so play a structural role in organisms for support or protection. Fibrous proteins can be subdivided into several different types:

 

· keratins, found in hair, fingernails, and bird feathers

 

· collagens – the most abundant proteins in a vertebrate body – found in connective tissues such as cartilage

 

· elastins, found in ligaments, around blood vessels.

 

Fibrous proteins are one of two main types of protein that have a quaternary structure; the other are globular proteins.