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?

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) _______.

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?

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

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

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

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

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) _______.