Protein Expression - Question (Jul/20/2005 )

If a protein is transfected into cells and over-expressed (which is clearly seen in a western blot), what is the significance of a greater inhibition of the over-expressed protein compared to the more moderate inhibition seen in the cell lysate or alternate, but less expressed isoform itself?

---

Proteolytic degradation of over-expressed protein (enhanced proteasome activity) - a homeostatic mechanism in the cell to maintain levels of that protein (either endogenous or overexpressed) or perhaps something the cell does to reduce the level of this over-expressed protein that it sees as foreign? Its just a thought.

---