Originally Posted by manimuth
debbie,
According to my knowledge, the phosphorylation of a protein does not affect its mobility in SDS-PAGE much and the reasons are these:
1) SDS covers each denatured protein with a strong negative charge and the negativity of PO4 is not enough to make a big difference in this charge.
2) PO4 also does not affect the protein mass or size by enough to make a significant difference in motility.
So, since the whole point of SDS-PAGE is to give proteins a negative charge proportional to their masses so that they will seperate according to size....AND phosphorylation affects neither the charge nor the mass, of a protein, to make a significant difference, phosphorylation will not affect the migration of a protein on SDS-PAGE by much.
Hope this helps.