Supersecondary Structures and Domains

Many proteins that have the same type of function have similar protein sequences consequently, domains with similar conformations are associated with the particular function. Many types of domains have been identified, including three different types of domains by which proteins bind to DNA. In addition, short polypeptide sequences within a protein direct the posttransla-tional modification and subceUular localization. For example, several sequences play a role in the formation of glycoproteins (ones that contain sugars in addition to the polypeptide chain). Other specific sequences indicate that a protein is to be bound to a membrane or secreted from the cell. Still other specific sequences mark a protein for phosphorylation by a specific enzyme. 

Sign in atwww.thomsonedu.com/login and explore a Biochemistry Interactive tutorial on the features of/3-turns and how they change the direction of a polypeptide strand. 

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