T/F All cells monitor their intracellular and extracellular environment and respond accordingly
True!
What are effector proteins?
When activated, these proteins change themselves to carry out whatever action the signal tells it to do
What are the 4 types of intercellular signaling?
- Contact-dependent
- Paracrine
- Synaptic
- Endocrine
Describe contact-dependent signaling
The cells must be directly touching each other (intimate conversation)
Describe Paracrine signaling
One cell secretes signals that the surrounding cells pick up (discussion among friends)
Describe Synaptic signaling
Neurotransmitters in neurons
Describe Endocrine signaling
Hormones (are signals) are secreted into the bloodstream and travels through the body to other cells (Public broadcast)
T/F Cells don't always need a signal to survive
False! Cells need a constant signal to tell them that they are alive
T/F Cells can only accept one type of signal at a time
False! There can be multiple signals that the cell can intake in one time
Do all cells respond in the same way to the same signal?
Nope! Depending on the type of cell that receives the signal, the outcome will be different
Describe the types of signals
- Small hydrophobic molecules (fatty acids, steroids)
- Dissolved gases (CO)
- Proteins/small peptides (growth factors EGF)
Describe the types of receptors
- Transmembrane proteins on cell surface
- Intracellular to catch small diffused signals
What are the 3 major classes of cell-surface receptors?
- Ligand-gated ion channels
- G-protein-coupled receptors
- Enzyme coupled receptors (kinases(brings 2 proteins together))
Second Messengers
They are the small chemicals that generate after the original signal binds the receptor. It goes on to bind to others proteins down its path
What are the 2 states in which a molecular switch protein can be in?
Active and inactive
The discussion video you chose about Ser/Tyr kinases and how it switches and affects the other
Phosphorylating a protein can lead to activating, deactivating it or signaling other proteins to bind to it. The kinases that phosphorylate the 3 amino acids (Ser, Tyr, Thr), Serine kinase can also phosphorylate Threonine as well.
How do heterotrimeric GTPases work?
A transmembrane proteins with one end outside (receptor) and one end inside (alpha, beta, gamma subunits). Once phosphorylated, the alpha subunit takes the GTP and is separated from the 2 other subunits to bind with other enzymes
How do monomeric GTPases work?
When it is inactivated, it is bound to GDP. A GEF (guanine nucleotide exchange factor), will switch the GDP out with a GTP to make the protein activated. To deactivate it once again, a GAP (GTPase-activating protein) will replace the GTP with a GDP.
What are scaffolding proteins?
A large protein that binds to a whole bunch of signaling proteins to prepare it for downstream signaling action.
Can Scaffolding proteins be preassembled?
Yes they can be preassembled, or assembled after getting a signal from the receptor
T/F Some proteins can contain only interaction domains and serve as adaptor/scaffold proteins
True
What do modular domains do?
They help determine which proteins will bind where on the cell. It helps to evolve new pathways
What does Src homology 2 (SH2) and phosphotyrosine binding (PBT) like to bind to?
Phosphorylated tyrosines
What does Src homology 3 (SH3) domains like to bind to?
Proline rich sequences
What does pleckstrin homology (PH) domains like to bind to?
PIP (a group of phosphates within a cell membrane)
Signal responses are _____ if it is changing existing protein conformation/phosphorylation and are ____ if it requires new transcription/translation
Faster/ slower
Signal responses over a signal concentration can be ______ in response to hormones, or ______ in response to a cell division signal
Gradual/ all or none
T/F Positive and Negative Feedback loops are very common in signaling pathways
True
What is P ositive feedback?
Stimulus ->A -> B ->makes more A.
It will increase the amplitude of the signal.
What does Positive Feedback do?
Makes the response persistent (bistable). Good for stable long term changes in the cell
What is Negative Feedback?
Stimulus -> A -> B-> inhibits A
It will dampen responses causing oscillations
What does Negative Feedback do?
It helps adaption and desensitization
T/F G-protein receptors are the smallest family of cell surface receptor
False. They are the largest family with 800 total and 150 orphans (don't know what it binds to)
How does G-proteins regulate production of cyclic AMP?
GPCRs depending on what they are coupled to will produce a Gs ( from stimulatory protein) or a Gi (from an inhibitory protein)
T/F All the cells use Ca2+ as an ubiquitous second messenger
True. All cells do
______ is an abundant protein that is allosterically activated by Ca2+
Calmodulin
Calmodulin binds to this molecule which serves as a short term "memory" device to respond to Ca2+ oscillations of high frequency
CaM kinases
How does NO (Nitric Oxide) mediate signaling between cells?
It is dissolved so they can easily diffuse through neighboring cell membranes to activate guanylyl and produce cGMP. That leads to the relaxing of smooth muscles.
What does activation of GPCR kinases (GRK) do?
It phosphorylates the receptor and causes binding of arrestin to prevent the signaling of molecules through G proteins.