Chemistry 532: Key to Homework 2

Signal Transduction

 

Useful websites:

http://geo.nihs.go.jp/csndb

http://www.grt.kyushu-u.ac.jp/spad/index.html

http://www.copewithcytokines.de/cope.cgi

http://sdb.bio.purdue.edu/fly/aimain/aadevinx.htm

 

The answers to the following questions can be found on at least one of the websites listed above.

  1. e MAP-kinase pathway (MAPK) to find out which molecules activate MAPK and which molecules are then activated by MAPK. Which molecule is phosphorylated by MAPK in response to TGF-b and what happens to this molecule after phosphorylation?

    It is Smad-1 which then goes into the nucleus and binds to a specific DNA sequence.

  2. Look up Ras and find the 1PLK crystal structure. Which form of Ras is represented by the structure, which mutant is it and who is the first author of the paper describing the structure?

    It is the CH P21 Ras protein with the G12P mutation complexes to a GTP analog submitted by A. Schedig (first author).

  3. Which protein is inhibited by Calphostin A and what is the IC50? Cite a journal reference that describes the compound’s activity.

    It is an inhibitor for PKC with an IC50 of 250 nM. It was described in J. Biochem. Pharm (1994) v47, p 373.

  4. The STAT1 molecule is directly activated by several molecules- list three of these.

    The IL-10 receptor, Tyk2 and JAK1.

  5. How many isoforms are there for the TGF-b cytokine? What is L-TGF? Is there a TGF-b knock-out mouse?

    There are at least five isoforms, L-TGF is a precursor form secreted by cells and yes, there is a TGF-KO mouse.

  6. In what cellular process is the Drosophila protein reaper involved in? Which human proteins are homologous to reaper and are they involved in a similar process? Which other Drosophila proteins are homologous with reaper and what cellular processes are they involved in?

    It is involved in programmed cell death and it is homologous to the human proteins Fas and TNFR1, which are also both involved in programmed cell death. The homologous fly proteins grim and wrinkled are also involved in programmed cell death.

  7. Can measurements of intracellular calcium fluxes be used to assay signaling by IL2? Justify your answer.

    If you’ve found something suggesting that IL-2 can trigger calcium it is acceptable. However, if you look at the SPAD database and the complete signaling pathway for IL2, PLC-g is not activated and, thus, it does not trigger calcium fluxes. It does activate Lck, which is involved in T-cell receptor signaling. Signaling from the T-cell receptor does activate PLC-g, but this requires ligand binding. Thus, one can draw a connection between calcium signaling and the IL2 receptor but, Il2 alone will not trigger calcium fluxes. It will enhance calcium fluxes that are triggered in response to T-cell receptor signaling.