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.
The interesting points to me were the following:
1. Some proteins are made by creating sub-assemblies first, then putting the pre-fab parts together, rather than cranking out a protein ab initio one amino acid at a time.
The details of how THAT process happened one mutation at a time would be pretty interesting :-)
2. Some proteins are cranked out one amino acid at a time, but according to one of your earlier posts, intermediate proteins come along (like scaffolding while constructing a skyscraper) to stabilize the intermediate structure.
This might lead one to think of a "chicken and the egg" conodrum, in which the cell needsthe protein which is being assembled one amino acid at a time, but without the stabilizing protein coming along at the right time, the energetically preferred conformation of the protein being assembled is not one biologically useful to the cell.
So (at first blush) one of two things needs to happen:
a) the cell "makes do" with some protein or other which happens to be laying around, in order to stabilize the being-built protein--presumably over time and generations the structure of the stabilizing protein changes to get better at its job--but not so much that it starts screwing up its original function. (I know, lotsa hand-waving here...)
or
b) the cell has to custom make the stabilizing protein first, before it tries to build the other protein, and just happens to get the size, shape, abundance of the stabilizing protein right, even before it is used.
Curiouser and curiouser, Bunter mine.
Cheers!
You'll not win at TicTacToe with this stradegy!