Which kinases phosphorylate B-Catenin? What happens next?
CK1 and GSK3, B-Catenin gets ubiquitylated and degraded by the proteasome.
what is the co-repressor that is bound to LEF1/TCF to suppress transcription?
What happens to B-Catenin in the absence of Wnt?
it gets degraded
How is B-Catenin released in the presence of Wnt to stimulate transcription?
Wnt binds to the receptor "frizzled" and co-receptor LRP, this leads to recruitment and activation of "dishevelled", then the "degradation complex" is recruited and CK1 and GSK3 can phosphorylate the LRP, the complex falls apart and B-Catenin is no longer phosphorylated and can enter the nucleus.
Once in the nucleus, how does B-Catenin stimulate transcription?
B-Catenin will bind to the LEF1/TCF, displacing Groucho, and inducing transcription of various genes
What is the function of STAT?
Provide a direct link between signal transduction across the cell membrane and transcription
Where are STATs found in the absence of ligand? What is there state?
in the cytosol, in an unphosphorylated state
T/F: STAT phosphorylates JAKs.
False, it's the opposite
If ligand binds to JAK, what is the pathway that follows?
The 2 JAK come together to cross-phosphorylate each other leading to the recruitment of STATs. STATS bind to JAKs, get phosphorylated, STAT is freed and dimerizes with another STAT in the cytosol, enters the nucleus to bind a particular DNA sequence and activate transcription.
What happens when EGF binds the receptor?
EGF cross phosphorylate, recruiting proteins Grb-2/Sos, the complex recruits inactivated-Ras which is bound to GDP, Ras is released, binds to GTP, then activated leads to activation of Raf1K-->MEK1/2-->ERK1/2 which is part of the MAP kinase pathway.
What do the MAP Kinase family pathways lead to?
The promotion of growth and diffentiation
ERK, JNK, and p38 are part of what pathway?
Map Kinase family pathway
What are the three examples of transcription factors that are phosphorylated by ERK1/2 or RSK?
Once phosphorylated by _______ Fos combines with______ to form __________ transcription factor complex.