Protein fold class

They describe groups of proteins that share similar amino acid and secondary structure proportions.

[1][2][3] Four large classes of protein that are generally agreed upon by the two main structure classification databases (SCOP and CATH).

[4] Common examples include the flavodoxin fold, the TIM barrel and leucine-rich-repeat (LRR) proteins such as ribonuclease inhibitor.

[8][9][10] IDPs cover a spectrum of states from fully unstructured to partially structured and include random coils, (pre-)molten globules, and large multi-domain proteins connected by flexible linkers.

The roles of such proteins include protection and support, forming connective tissue, tendons, bone matrices, and muscle fiber.