Concept #1: Map of Lesson on Biosignaling Pathways

Concept #2: Insulin Growth Factor Signaling via Ras Pathway

Example #1: G proteins such as Ras are activated when:

Practice: In the insulin signaling pathway to activate the protein Ras, activated IRS-1 binds to ___________.

Concept #4: Ras Pathway Activates the MAPK Signaling Pathway

Example #2: All of the following are true in the Ras and MAPK pathways EXCEPT:

Concept #5: Termination of Insulin Signaling as a Growth Factor

Practice: The monomeric G-protein Ras is activated by _______________, while _______________ helps turn Ras off.

Concept #6: How to Remember Insulin RTK Signaling as a Growth Factor?

Practice: Place the insulin RTK signaling events in order from 1-7:

a) Ligand binding results in autophosphorylation of the receptor tyrosine kinase ______.

b) MAPKK (Mek) phosphorylates MAPK (Erk) ______.

c) Sos binds then activates Ras ______.

d) Receptor tyrosine kinase phosphorylate IRS-1, which binds the SH2 domain of Grb2 ______.

e) Ras activates MAPKKK (Raf-1) ______.

f) MAPK (Erk) activates transcription factors to regulate mRNA synthesis ______.

g) MAPKKK (Raf-1) phosphorylates MAPKK (Mek) _______.

Practice: Ras is estimated to be responsible for 30% of human cancers. Most mutations in Ras prevent the protein from binding GTPase-activation proteins (GAPs). What is the effect of this mutation on the signal transduction?

Practice: Insulin is one of the hormones/growth factors that will activate the Ras and MAP kinase pathway. Concerning this system, all of the following are true EXCEPT

Practice: All of the following are true in the Ras and MAPK pathway EXCEPT:

Practice: Guanine Exchange Factors (GEFs) bind Ras-GDP and promote dissociation of bound GDP to be replaced by GTP. GTPase Activating Proteins (GAPs) bind Ras-GTP and stimulates GTPase activity of Ras. How is the downstream signal affected by the presence of GEFs and GAPs?