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Sorry about this not being exactly CCP4 related, but I think it is still of general interest to the structural biology community: I am dealing with a membrane protein which seems, on the surface, to present a contradiction: We know from western blots and other data that this protein forms oligomers vehemently, which are all but impervious to monomerization under the most ruthless conditions--we cannot completely monomerize it. We have tried DTT, EDT, BME, all concentrations of SDS, PFO, temperature, and salt, and in various combinations (further suggestions are welcome.) Suffice it to say, this thing is a bona fide vicious oligomer. Here is the paradox: the functional data, on the surface, seem to imply that the protein acts independently, as if a monomer, without being influenced by its (tight) oligomeric partners, even though we think the functional mechanism is a conformational change. Is such a thing observed in the biochemical world? Are there any homo-oligomeric proteins out there, membrane-bound or otherwise, which exhibit conformational changes, and yet the protomers do not influence each other? If so, if the oligomerization has no functional significance, and the subunits do not exhibit crosstalk, what on earth is the reason for their oligomerization? All hypotheses and especially references would be greatly appreciated, Jacob Keller *********************************** Jacob Keller Northwestern University 6541 N. Francisco #3 Chicago IL 60645 (847)467-4049 [log in to unmask] ***********************************