...and in absence of TM domains and the 2D restriction of the membrane
they will probably not dimerize as free domains in solution now
suddenly gained the freedom of 3D diffusion
On 11/12/2008, at 19.03, Nathaniel Echols wrote:
On Thu, Dec 11, 2008 at 8:09 AM, Santarsiero, Bernard D.
<b...@uic.edu> wrote:
In parallel with the discussion around this off-CCP4-topic, are they
any
good examples of the opposite case, where the protein is a monomer in
solution (as evident from light scattering, MW determination through
centrifugation, EPR, etc.) but crystallizes as a dimer or higher
multimer?
There are several families of receptor kinases that behave like
this, specifically EGFR in humans and some of the Ser/Thr kinases in
M. tuberculosis. The kinase domains alone have very low
(millimolar) affinity but dimerization in response to an
extracellular signal is required for activation. In both cases the
activation mechanisms were not understood until the dimeric crystal
structures were (accidentally) obtained, and were later confirmed by
biochemical experiments:
http://www.ncbi.nlm.nih.gov/pubmed/16777603 (PDB IDs: 2gs2, 2gs6,
2gs7)
http://www.ncbi.nlm.nih.gov/pubmed/17242402 (and cited papers - PDB
IDs: 1mru, 1o6y, 2fum, 2h34)
