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Re: SDS-PAGE mobility phosphopeptides




>
>Is there anybody why phosphorylated protein migrates slowly than
>dephosphorylated protein on SDS/PAGE?
>
        The major reason is that the phosphorylation induces a structure on
the protein.  Migration through the pores of the gel depends on the protein
forming an "ideal" random coil--anything that perturbs this random coil
structure, such as phosphorylation or formation of a disulfide bond, will
cause the protein to run slower (or shift up).  The specific pore structure
of the gel will affect the degree of gel shifting.  That is why a different
amount of cross-linker is used in gels where one is trying to detect gel
shifts.

        The presence of phosphate can also prevent SDS from associating
with the protein properly, but this probably requires a lot of phosphate
added to be significant.

Katheryn Resing