Quaternary Protein Structure:
Three-Dimensional assembly of subunits

    The hemoglobin molecule is a tetrameric structural protein that comprises two alpha and two beta subunits. The arrangement comprises two symmetrical alpha + beta subunit halves. Other quaternary structures may comprise a dozen or more polypeptides, all of which are distinct. [The inorganic heme groups are modifications of the tertiary structure of the individuals monomers, but are not typical of quaternary structure].

Figure © 2002 by Griffiths et al. ;
All text material ©2010  by Steven M. Carr