There's gotta be some reference to Dr. Seuss here.
As long as you don't drag in such PC BS as The Butter Battle Book or The Lorax
Full Disclosure: Or maybe the turtles are denizens of San Francisco...
Yesterday you asked about hemoglobin. I got some info, but it's limited.
Hemoglobin is made up of four proteins, 2 alpha subunits and 2 beta subunits. These subunits fold correctly by themselves without help.
When the tetramer comes together the first binding is an alpha and beta subunit then two of these dimers bind. This data is infered from both assembly experiments and from denaturing experiments.
Final molecule looks like:
oo
xx
where o is an alpha subunit and x is a beta subunit.
If you want more information, I'll have to take a pass since I have not got a good library at my disposal.