Signal Transduction Flashcards
What do most things that affect cell activity or function do?
They act on membrane-bound receptors that control signalling proteins via the production of second messengers.
How many kinases and phosphatases are encoded by the human genome?
Approximately 520 kinases and 150 phosphatases.
What are the two main types of kinases?
- Tyrosine kinase
- Serine/threonine kinase
What are the two types of GTP-binding proteins?
- Trimeric G proteins
- Monomeric GTPases
What is a G-protein-coupled receptor (GPCR)?
A cell-surface receptor coupled to trimeric G proteins that bind either GTP or GDP.
How many membrane spanning regions do all GPCRs have?
7 membrane spanning regions.
What happens when a ligand binds to a GPCR?
It activates the associated G protein, which inhibits/activates a downstream enzyme to generate an intracellular second messenger.
What triggers G protein activation?
Binding of the ligand to the receptor changes its conformation, causing it to bind to the Gα protein.
What is the effect of GDP being displaced by GTP?
It triggers Gβγ dissociation activating downstream pathways.
What are the three components required for the G-protein-coupled receptor system?
- A receptor
- A transducer (G-protein)
- An amplifier (adenylate cyclase)
What is the role of Protein Kinase C (PKC)?
It phosphorylates a wide variety of substrate proteins on serine and threonine residues.
What initiates the fertilization process in eggs?
Calcium signals triggered by PLC-ζ.
What does increased cAMP do in the context of the b2 adrenergic receptor?
It increases the intracellular concentration of cAMP.
What is the function of the cAMP response element binding protein (CREB)?
It binds to cAMP response elements in gene promoters to activate transcription.
What does cholera toxin stimulate?
Overstimulation of cAMP production, leading to rapid fluid loss and dehydration.
What do receptor tyrosine kinases (RTKs) activate?
Ras, which is a small GTPase.
What are some cellular processes regulated by the Ras superfamily?
- Proliferation
- Cytoskeletal dynamics
- Membrane trafficking/vesicular transport
What is the role of the EGFR receptor in cancer?
It activates Ras, which stimulates gene transcription via other kinases.
What are the main components of the MAPK pathway?
- MAPK
- MAP2K
- MAP3K
True or False: Signal transduction is required for translation of cellular signals into events.
True
Fill in the blank: The _______ pathway is involved in the context of G-protein signalling.
Phospholipase C/Ca2+/Protein Kinase C
What is the resting calcium concentration in cells?
~100 nM
What is an activated calcium concentration range?
0.5-1 μM
What happens to CREB when it is phosphorylated?
It becomes active and can activate transcription.
How many types of Gα subunits are there?
20 types of Gα subunits.
What do Gβ/γ dimers do?
- Gate ion channels
- Stimulate PLA2
- Stimulate adenylate cyclase
- Stimulate PLC-β, PLC-ε, and PLC-η
What is the primary function of adenylate cyclase?
To synthesize cAMP from ATP.
What type of signalling pathways are interconnected?
Signalling pathways involved in various cellular processes.
