Question

Question #a3442

Answer 1

Collagen, is a structural protein and as a functional protein, is found in the quaternary structure. But, it isn't that simple.

Explanation:

These structural proteins that are found in the extracellular matrix, (outside cells in semi-solid materials to trap water) are important at creating adhesive protein networks between cell populations. The many genes that are used to make the many varieties of collagen form two types of collagen ( fibril forming and non-fibril forming.)

You should review the concept of primary, secondary, tertiary and quaternary structures in proteins (Google will help with that.) Simply: primary is a strand of amino acids, secondary is the manner in which those amino acids fold upon themselves (attraction and repulsion), tertiary structure is the sum of the intra-molecular bondings that create the "active" protein in normal physiological environments, while the quaternary structure is the sum of "active" proteins needed to function in a complex.

Here is an older citation that will help with the complexity of the question that you asked:
The Family of Collagen Genes
Annual Review of Biochemistry
Vol. 59: 837-872 (Volume publication date July 1990)
DOI: 10.1146/annurev.bi.59.070190.004201

cheers.