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Lecture

Notes taken during lecture


Department
Biology
Course Code
BIO120H1
Professor
Jean Jiang Nash

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MAP kinase cascade
Ex. 2 signalling pathways in yeast
Yeast DO mate alpha and beta mating types
Glycerol so cell doesnt desiccate
Same MAP kinase
oWhy doesnt activate wrong pathway?
Because of scaffold proteins, which recruit subset of MAP kinase
Output of each set of proteins can be different so the two
pathways, at the same part, may have different proteins
oLeaves scaffold protein and translocates to nucleus
oCassette idea
Possible to activate one cassette independent of another
JAK/STAT enzyme associated receptor through protein protein interactions
Janus associated kinase
E.g. Jak1, Jak2, Jak3
oEach with different substrate specificity
Transphosphorylation activate
Receptor phosphorylation for docking, for phosphorylation of stat, STATs
dimerize
Binds to DNA turning on or off gene
oSTAT is a transcription factor
EXAMPLE: erythropoietin differentiation red blood cell
Its a cytokine
Erythropoiesis generation of red blood cells
Target genes one of which is haemoglobin
EPO receptor important
oWild type mouse liver is red, where red blood cell production
oKnock out EPO receptor homozygous mutant mouse will grow, without
red blood cells, runs out of oxygen and dies
TGF-beta signalling in animals
Transforming growth factor
oNormal tissue type want to transform it into cancer cell us TGF
oFunctioning as a tetramers***
oEach found as homodimers
oActivated complex = tetramer
oUnidirectional phosphorylation event after tetramerization
oType 2 receptor phosphorylates Type 1 receptor
Dimer that binds is either Smad 2/3 or Smad4 dimer
Dont need to know example of target gene
Turning off a pathway
oDifferent ways
oKnow
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