Cytosolic protein on membrane

Emir Khatipov khatipovNO at
Tue Sep 17 12:39:51 EST 2002

Sorry I cannot provide you with any references, but is widely known that
some proteins would associate/dissociate with membranes depending on various
physical and chemical factors. Are you sure that your experimentally
determined location of the protein is not an artifact of the method you used
to prepare microscopic sections? As far as I remember, preparation of cells
for EM includes freeze-drying, which may result in artifacts. I am not sure
that one can use EM to test localization of proteins. For example, it is
often necessary to optimize mono- and divalent ion concentrations in order
to achieve dissociation of proteins from membranes, including cytoplazmic
proteins that simply stick to membranes after the cell is broken. How can
you say that the protein was bound to membrane _before_ you froze and dried
the cells?

"Luc CAMOIN" <lc at> wrote in message
news:B9AD0ECA.18CE8%lc at
> Dear all,
> I'm studying membrane proteins from human spermatozoa. We purified and
> identified one of these proteins as "Triose Phosphate Isomerase". The
> location of this protein was confirmed by electronic microscopy and is on
> the acrosomic membrane. In literature, this protein is known as cytosolic.
> My questions are: Do you have an idea by which mechanism this protein is
> located on the membrane? Does anybody have a reasonable explanation for
> that? Does anybody know a reference showing a cytosolic protein located in
> membrane?
> Thanks for all answers.
> ---

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