Cell signaling - copy
A cell's response to a signal can be:
Either fast or slow, depending on the signal.
Which of the following is NOT listed as a common type of ligand?
Carbohydrates
Which of the following is NOT considered one of the three main classes of cell-surface receptors?
Nuclear steroid receptors
G-protein coupled receptors (GPCRs) are also known by which other name, referencing their structure?
Serpentine receptors
Which type of cell signaling involves local mediators acting on nearby cells?
Paracrine signaling
What is the third general step in signal transduction, following signal contact and transduction/amplification?
The receiving cell responds.
Which statement best describes the primary role of cell signaling?
To enable cells to communicate and respond to their environment.
What is the nature of receptors in cell signaling?
They are almost always proteins with specific 3D shapes.
What is the immediate effect of ligand binding to a receptor?
It induces a conformational change in the receptor protein.
What is the primary mechanism by which some intracellular signaling proteins act as molecular switches?
By undergoing phosphorylation to change activity.
Upon activation of a trimeric G-protein, what is the immediate consequence for the Gα subunit?
It dissociates from the Gβγ complex.
What is the largest class of enzyme-coupled receptors?
Receptor Tyrosine Kinases
What is the primary enzyme activated by cyclic AMP (cAMP) in many signaling pathways?
Protein Kinase A
In the MAP kinase pathway, which protein acts as the MAP kinase kinase kinase (MAPKKK) immediately downstream of activated Ras?
Raf
From what precursor molecule are steroid hormones like cortisol and estrogen derived?
Cholesterol
Which protein acts as a calcium-binding messenger, undergoing a conformational change to activate CaM-dependent kinases?
Calmodulin
Which enzyme is responsible for converting ATP into cyclic AMP (cAMP), a common intracellular second messenger?
Adenylyl cyclase
What is the primary action of kinases within signaling pathways?
Adding phosphate groups
Olfactory receptors, responsible for detecting odors, belong to which class of receptors?
G-Protein-Coupled Receptors
The PI-3-kinase-Akt pathway is activated by RTKs and involves the phosphorylation of what type of molecule by PI3-kinase?
Inositol phospholipid
Which enzyme, when activated by a G-protein, cleaves inositol phospholipid to produce IP3 and DAG as second messengers?
Phospholipase C
Canonical G-Protein-Coupled Receptors (GPCRs) are often referred to as 'serpentine receptors' due to their characteristic number of transmembrane passes. How many transmembrane passes do they typically have?
Seven
Activated Erk/MAPK can enter which cellular compartment to phosphorylate transcription factors and alter gene expression?
Nucleus
Which characteristic best describes the speed of response typically mediated by ion channel coupled receptors in the nervous system?
Very fast
What two molecules are immediately produced by Phospholipase C activity that act as further intracellular messengers?
IP3 and DAG
The Estrogen Response Element (ERE) is a specific DNA sequence that acts as a binding site for which complex?
Estrogen receptor dimer
Upon ligand binding, what is the initial key event that activates Receptor Tyrosine Kinases (RTKs)?
Receptor dimerization
Which type of receptor primarily functions by binding to Hormone Response Elements (HREs) on DNA to regulate gene transcription?
Nuclear receptors
Which type of ion channel is not receptor-mediated and allows for the direct passage of small molecules between adjacent cells?
Gap junction
At the neuromuscular junction, the binding of acetylcholine to nAChR directly causes an influx of which ion into the cell?
Sodium ions
The insulin receptor is a classic example of which type of cell surface receptor, activating both MAPK and PI3K/AKT pathways?
Receptor Tyrosine Kinase
What type of hormone is insulin, produced by the pancreas, which regulates blood glucose levels?
Peptide hormone
What common protein domain found on intracellular signaling proteins often binds to phosphorylated tyrosines on activated RTKs?
SH2 domain
Ras is an example of which type of G-protein?
Monomeric G-protein
Fibroblast Growth Factors (FGFs) are a family of signaling proteins primarily involved in what cellular processes?
Promoting cell growth and division
Akt and Bad are shown to interact in vivo. This interaction is described as being independent of phosphorylation at which specific site?
the Serine 136 residue
Which experimental technique was used to quantify cell death in the Datta et al. study?
TUNEL assay method
How does the phosphorylation of Bad S136 by Akt contribute to cell survival?
It inhibits Bad-induced apoptosis.
While Akt phosphorylates Bad at S136, a different kinase is responsible for phosphorylating Bad at S112. Which kinase is this?
the PKA kinase
The main focus of the Datta et al. study described in the journal club was to investigate how Akt phosphorylation of Bad affects which cellular process?
'cell intrinsic' apoptosis
The phosphorylation of Bad by Akt in response to PDGF is dependent on the activity of which upstream enzyme?
PI3K pathway
An 'Active Akt' construct, tethered to the membrane, is described as being constitutively 'on.' This means it is active without the need for which of the following?
upstream signaling cues
What is the specific serine residue on the Bad protein that Akt phosphorylates in response to survival signals?
Serine 136 residue
One of the identified limitations or areas for future work in the study of Akt and Bad interaction includes a reliance on what experimental approach?
protein overexpression
In the 'cell intrinsic' death machinery, Bad is considered a pro-apoptotic protein because it directly sequesters which anti-apoptotic protein?
Bcl-2 family member
Neurotrophins signal through which two general types of receptors?
RTK receptors and low affinity p75 receptors.
What is the primary function of Bcl-2 proteins in the regulation of apoptosis?
Blocking apoptosis by inhibiting pro-apoptotic proteins.
Which of the following is a general role of apoptosis in biology?
Sculpting of tetrapod digits
How does apoptosis typically differ from necrosis?
Apoptosis forms apoptotic bodies for phagocytosis.
What is a primary function of Nerve Growth Factor (NGF) for neurons?
Promoting neuronal cell survival.
The extrinsic pathway of apoptosis is typically initiated by the binding of ligands to which type of cell surface receptor?
Fas death receptors
A critical step in the intrinsic pathway of apoptosis involves the release of which molecule from mitochondria?
Cytochrome C
Active Akt, stimulated by survival factors, prevents apoptosis by phosphorylating which protein?
Bad
Caspases, central to apoptosis, belong to which enzyme family?
Cysteine-aspartic proteases
How do survival factors prevent apoptosis by affecting the Bcl2 gene?
They promote Bcl2 gene transcription.