Mutagenising phosphorylation sites

David Micklem drm21 at
Mon Jul 31 14:29:17 EST 1995

Dear All,

I wonder if someone out there could give me some advice about mutagenising
Serine residues suspected of being phosphorylation sites.

As far as I can gather, it is common to change the Serine to an Alanine to
mimic the always-unphosphorylated state, and to an Aspartate to mimic

Is this correct?  Does anyone know why this is done rather than Serine->
Cysteine, which should be both unphosphorylatable and (presumably - I'm
not a great chemist) more chemically similar to Serine?

Similarly, a naive look at the structures of phosphoserine, aspartate and
glutamate suggest to me that glutamate is more like phosphoserine than
aspartate is.

Any guidance on why Ala and Asp are used instead of Cys and Glu (or vice
versa) would be much appreciated.

Thank you,


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