signaling Flashcards
what are the 3 steps in every signal
- reception
- transduction: signal amplification
- phosphorylation cascade
- response
what are 2 driving forces in development? describe each
cell fate determination
- indifferentiated cells take on fates (differentiate) during embryogenesis
morphogenesis
- “creation of form”, cell types must be organized properly into tissues, organs, etc
what is a transcription factor?***
responsible for remodeling the chromatin to give/block RNAP II access to a gene.
3 domains:
- dimerization
- trans acting (activate or repress transcription)
- DNA binding
what is the function of transacting element?***
- acetylation of histones activates transcription
- de-acetylation of histones blocks transcription
what are 2 classes of TF?
- zinc finger
- homebox
what is cyclopamine and what does it do?
- it is a teratogen
- blocks the action of smoothened
- embryos exposed to cyclopamine resemble those that are defective in hedgehog signaling
describe notch signaling -lateral inhibition
- a cell expresses more delta on its surface than its neigbors
- notch signaling in the surrounding cells inhibits the expression of genes required for neural differentiation
define protooncogenes and tumor supressors
protooncogenes: function as positive regulators of cell growth. induce tumors through a gain of function
tumor supressors: function as negative regulators of cell growth. loss of function results in tumor growth
name and define the 2 types of receptor ligands
agonist: binds and activates
antagonist: binds and shuts down
what are the 5 subtypes of muscarinic receptors and what do they do
M1, M3, M5: coupled to g type g proteins–> activates phosphorylase C
M2, M4: coupled to g type g proteins–> inhibits adenylate cyclase
what are muscarinic receptors?
- bind acetylcholine but are GPCRs
what are the 3 subunits of G proteins? what binds to GDP?
- alpha, beta, gamma
- alpha binds to GDP and then
describe the cycle of G-protein activation/inactivation***
- ligand binds to receptor, GDP is replaced by GTP
- alpha subunit dissociates from beta and gamma (b and g always travel together)
- dissociation allows GTP bound G protein to interact with effector enzymes, either activating/inactivating them
- alpha subunit will hydrolyze the GTP to GDP
- after hydrolysis, 3 subunits recombine, this completes cycle
list 4 second messengers and what they are made by
- cAMP (made by adenylate cyclase)
- IP3 (generated by phospholipase C)
- DAG (generated by phospholipase C)
- calcium (can do many things, including activate cellular machinery)
what do phospholipase C and DAG do as intermediates
phospholipase C cleaves PIP2 to form DAG and IP3
what does IP3 do
IP3 is a second messenger that binds to gated calcium channels, allowing Ca++ to enter the cell
what will calcium do once inside the cell?
activate various proteins, leading to cellular responses
what are protein kinases? what can they do?
- enzymes that transfer phosphate groups to hydroxyl groups
- they can regulate many different types of protein by transfer of a phosphate group
what are receptor tyrosine kinases? what are the 4 domains of every RTK?
- both receptors and enzymes
- membrane embedded proteins
- 4 major domains
- extracellular ligand binding domain
- transmembrane
- intracellular tyrosine kinase domain
- intracellular regulatory domain
describe the process RTKs go through.
name one example
- signaling molecule binds to ligand on the cell membrane
- must form dimers
- 6 unphosphorylated tyrosines become fully active by being phosphorylated by ATP (becomes ADP)
- the now fully posphorylated dimer activate inactive relay proteins that will trigger cellular responses
example: insulin
what are cytokine receptors
what are all cytokines
what three hormones have the structure of cytokine receptors
- diverse class of signaling molecules
- all cytokines are peptides, proteins or glycoproteins
- growth hormone, prolactin, erythropoietin
describe intracellular or nuclear receptors
- bind to hydrophobic molecules
- located on cell interior sometimes in nuclear membranes
- ligand receptor-complex often functions as a ligand dependent TF
