Signal Transduction 2 Flashcards
EnZ linked receptors include
Tyrosine kinase linked
serine/threonine kinase-linked
Protein phsphatase-linked
Guanylyl cyclase linked
Two forms of Tyrosine kinase linked receptors
single protein w/ 1 transmembrane domain that dimerizes upon ligand binding
receptor has 2 subunits to form a tetramer upon binding
Tyrosine kinsae receptors have intrinsic
tyrosine kinase activity upon phosphorylation
EGF tyrposine kinase receptor is inactive as;
active as:
inactive a monomer
active as dimer
PDGF tyrosine kinsase receptor is incative as:
active as:
inactive as: monomer
active as: dimer
Insulin receptor is a tyrosine kinase receptor that is inactive as:
active as:
inactive as dimer
active as tetramer
Each TK receptor has ______ domain with tyrosine kinase activity
cytoplasmic
Activation of Tyrosine Kinase receptors is dimerized and activated by:
Trans-autophosphorylation
One dimer is activated by phosphorylation, it in turn phosphorylates the other unit back. Concept is called
Trans-autophosphorylation
After trans-autophosphorylation we bind:
intracellular molecules
Tyrosine kinase receptors are key for:
-regulation of cell proliferation and differentiation
ligands of tyrosine kinase include:
hormones like insulin
GFs like EGF, PDGF and VEGF
What receptors play imporant role in onogenesis and are targets of chemotherapies
Tyrosine kinase receptors
Receptors are first part of signal transduction and provide
specificiy
Receptors and their ligand are key, but we need what other guys to transduce a signal through cytoplasm into nucleus
intracellular signal molecules
G proteins Second messengers Proteins kinases and Protein phosphates Transcription factors are all examples of:
Intracellular signal molecues
Examples of intracell signal molecules
G proteins
Second messengers
Proteins kinases and Protein phosphates
Transcription factors
proteins that bind DNA and regulate transcription of gene
Transcription factors
CREB is :
cAMP response element biding protein
ubiquitous TF that activates many differnt genes
ubiquitous TF that activates many differnt genes
CREB
Myc, Fos, Jun are examples of
transcripion factors
What two things do signal transduction cascades regulate as far as TFs are concerend
Regulate it’s nuclear translocation and it’s ability to bind to DNA
What Regulates TF’s nuclear translocation and it’s ability to bind to DNA
signal transduction cascades
What do activated transcription factors do?
induce transcription by activating RNA polymerase–> get transcription of mRNA from target gene
Why do we want TF to activate RNA polymerase
bc then it will transcribe mRNA of target gene
Trend of TF;s is:
P’d by Protein Kinases will:
de-“d by protein phosphorylses will:
PKs will activate
PPs will inactivate
What aa do Protein kinases like to add P’s to
ser/threonine/tyrosine
PKA, PKC, Ca/calmodulin dependent kinase and MAP kinases are examples of
Serine/threonine specific PK’s
Tyrosine kinase-linked receptors like EGF and cytoplasmic kinases like Src and Abl are spefic for which protein kinase
Tyrosine specific
What kinases have dual specificiy and phosphorylate both tyrosine and threonine
MAP kinase kinases
The activity of a protein is often regulated by one/many kinases and phosphorlyases acting on a protein
MANY
What regulates activity of kinases and phosphatases
via second messengers
what does a protein kinase need to do it’s job
ATP
Phosphorylate protein is likely to
interact with dif effectors (more likely to then the d’Pd guy)
Small diffusible molecules generated in response to ligand-receptor interaction
second messengers
Second messengers will:
activate downstream effectors
cAMP is made when:
alpha sub activates adenylyl cylase : will will convert ATP–> cAMP
how does activated adnelylyl cyclase make cAMP
ATP–> cAMP
what does cAMP do?
acitates PKA
what activtes Protein kinase A
cAMP from activated adenylyl cyclase
DAG and IP3 are examples of
second messengers
How is DAG and IP3 made
Alpha-q will turn on Phospholipase C (PLC)–> PLC cleaves PIP2 to generate DAG and IP3
What do we generate from PIP2 and what enZ does this?
DAG + IP3 via PLC (acivated by alpha-q)