Protein dimerisation in SDS-gel

Vadim Tsvetnitsky vadtsvet at
Mon Feb 5 04:25:46 EST 1996

In article <4e2qiv$2rp at>, Mick Partis <mick.partis at> says:
>davesmith at wrote:
>>Lutz Essers <uj44228 at> wrote:
>>>My question is: Has anyone seen protein dimerisation in a SDS-gel, or are there any 
>>>comments or publications about this phenomenon? If so, could you please refer me.
>>We asked the same question about 4 years ago when we saw dimers of our
>>protein in SDS-PAGE.  Since we've purified our protein, we've seen as
>>high as trimers by Coommassie and hexamers when western blotting
>>SDS-PAGs.  The only other instance in the literature that we are aware
>>of with respect to SDS-resistant dimerization is the protein that Don
>>Engelman studies--glycophorin A.  It just happens to also be an
>>integral membrane protein.  The SDS-resistant character is a result of
>>residues in the transmembrane domain.  ...
>There is also the case of the outer membrane proteins (Porins) from E. 
>coli and S. typhimurium.  Trimers of these are stable in SDS (even in the 
>presence of 8M urea), but will break down into monomers when heated.  The 
>other notable point about porins is that although they are integral 
>membrane proteins, they are composed mainly of beta-structure. There are 
>descriptions of the SDS stability in Tokunaga, M et al. (1979) European 
>J. Biochem. 95: 441-448 and in Yu, F et al. (1979) FEBS Letters 100: 
>Mick.Partis at HRI.AC.UK         Horticulture Research International
>Tel: 01789-470382
>FAX: 01789-470552

Even small very well soluble cytoplasmic proteins like acyl-CoA-binding protein studied 
in this lab can form di and tri-mers on SDS-PAGE. No beta structures is present in this protein,
it's all-alfa helixes (by NMR). Its structure is in PDB if you're interested.


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