Return to the top. There are a number of ways to represent the folding of a protein and the arrangement of secondary structure elements within the tertiary structure. While these simplifications don't show the sidechain and mainchain interactions that hold the structures together, they do reveal the folding pattern. Examination of such diagrams reveals recurring structural patterns in protein folding. In this case, alpha helicies are red circles, columns and twists.
Beta sheets are green squares, arrows and ribbons with arrows.
At the simplest level, proteins can be classified by their content of secondary structure. However, there are some proteins where turns and disulfide bonds seem to be more important considerations. The 4 helix bundle of the cytochrome is a common motif. Of course, many proteins are a mix of alpha helicies and beta sheets. Return to the top.