How could shortened RTK that only includes cytoplasmic domain be a molecule that promotes tumor growth when it is introduced into a cell?
The genomes of viruses that promote tumor growth often encode a gene for a protein that resembles receptor tyrosine kinases (RTKs) that activate cell growth. Interestingly, these proteins are shortened versions of the RTK that only includes the cytoplasmic domain. They lack the extracellular domain of the RTK that binds to the signaling molecule or ligand. Make an informed prediction: How could a shortened RTK that only includes the cytoplasmic domain be a molecule that promotes tumor growth when it is introduced into a cell?
- Ted KLv 71 month ago
Simplest inference is that the extracellular domain--upon ligand binding--has a modulatory effect on whatever it is that the cytoplasmic domain is doing. Lose that modulatory effect by eliminating the ligand-binding domain and normal cytoplasmic function is lost--in this case the result is promotion of tumor growth, an effect that would otherwise be repressed in the wild type RTK.
So, in this case, the normal (complete) RTK, i.e. intact cytoplasmic + extracellular domains, is a ligand-dependent tumor supressor. Lose the capacity to bind ligand and tumor suppressor activity is lost.