what is your conclusion about diagnosis of cancer for Laura and Joyce and why? W
ID: 83803 • Letter: W
Question
what is your conclusion about diagnosis of cancer for Laura and Joyce and why? What do you mean by proto-oncogene and tumor suppressor gene? Ras is a proto-oncogene product and PTEN is a tumor suppressor gene product. Do you agree with this statement? Justify your answer. (A) There are eight Smad proteins (Smad1, ......Smad8) involved in signal transductions through TGF-beta pathways. If you want to inhibit the TGF-beta pathways efficiently by down- regulating one of the Smad proteins, then which one will you chose and why? (B) 'Px' is a protein which normally resides in the cytosol, but when the cells are treated with EGF, 'Px' immediately moves towards the cell membrane. Can you name (with reason) the probable domain(s) the protein has, which is/are responsible for such translocation? You discovered a new signaling pathway where the ligand Lx binds with its cognate cell surface receptor Rx and causes up-regulation of cytosolic Ca^+ 2 level. Can you suggest a downstream cascade initiated as a result of Lx-Rx binding which finally caused the up-regulation of cytosolic Ca^+2 level?Explanation / Answer
during TGF beta-Smad signalling pathway TGF beta binds to receptor and phosphorylation of regulatory Smad 2 and 3 takes place. this phosphorylated Smad 2 and 3 has high affinity for Smad 4 which is also called coSmad. phosphorylated RSMAD/coSMAD complex enters into the nucleus and binds with transcription promoters and start the transcription of DNA.
if we inhibit Smad 4 protein then we will down regulate the TGF beta pathway because this coSmad binds with the phosphorylated Smad 2 and 3 and then it enters into the nucleus for start of transcription.
2) EGF domain binds with the receptor and starts pathway activation. the first recruited protein have homology domain with the transmembrane receptor. because of this domain it binds and phosphorylate other recruited proteins and activates signaling pathway.
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