Dr. Paul's Virtually Biology Show.
Q
Quaternary
structure. The fourth level of protein structure. This arises
when different protein molecules come together to form a larger unit. For example,
Hemoglobin actually is composed of four protein units. The ultimate in quaternary
structure may be the microtubules in the cytoskeleton which are made of 10's of
thousands of protein units, each unit being a molecule of a protein called tubulin.
Actually each tubulin itself is composed of two protein sub units. So what do
we call this "Quintary structure??"