Tertiary Structure Domains, Folds, and Motifs

Abstract

Synopsis Proteins are complex and irregular structures; however, proteins possess regions of regularity at a local level in the form of secondary structure elements such as alpha helices and beta sheets. Secondary structure elements can combine to form structural motifs that are found in a variety of proteins. Many different motifs may be combined to form stably folding protein domains. Protein domains are regions of a protein that can stably fold and possess a certain function. Proteins may be made up of one or many domains. Each protein domain has a fold, which refers to the arrangement of secondary structure elements in that domain. Relatively few distinct folds exist with respect to the number of protein sequences; accordingly, one fold may be utilized by many different proteins to perform a range of functions.