Quarternary Protein Structure

    The structure shown has two subunits, each comprising three alpha helices and three beta sheets. Note that the subunits are held together by ionic bonds between two beta sheets running in opposite N-C direction. [The two subunits are said to show a dyad axis of symmetry].

Figure © 2012 TA Brown, Introduction to Genetics (1st ed.); additional text © 2014 by Steven M. Carr