Lecture 8 - Signaling Mechanisms Flashcards
list the major examples of signaling mechanisms
- Endocrine
- Paracrine
Autocrine
Neurotransmitters
Neuroendocrine
• Signaling molecules released by one cell act on neighboring
target cells.
A. Endocrine
B. Paracrine
C. Autocrine
D. Neurotransmitters
E. Neuroendocrine
B. Paracrine
• Cells respond to signaling molecules that they themselves
produce.
A. Endocrine
B. Paracrine
C. Autocrine
D. Neurotransmitters
E. Neuroendocrine
C. Autocrine
• Signaling molecules (hormones) are secreted by specialized
endocrine cells and transported through the circulation to target
cells at distant body sites.
A. Endocrine
B. Paracrine
C. Autocrine
D. Neurotransmitters
E. Neuroendocrine
A. Endocrine
The G protein consists of several subunits. Which of the following subunits exchanges its GDP for GTP when activated?
A. Alpha subunit
B. Beta subunit
C. Gamme subunit
D. Delta subunit
A. Alpha subunit
In the ERK-MAP kinase pathway, activation of the GTP binding protein Ras interacts with Raf kinase. Raf phosphorylates and activates which of the following?
A. cAMP
B. MEK
C. ERK
D. Elk-1
B. MEK
In the JAK-STAT pathway, a ligand binds to a membrane receptor. Associated with this receptor is molecule “A”. Molecule “B” binds to molecule “A”, resulting in the phosphorylation and dimerization of molecule “B”. What is the identification of molecule “B”
A. JAK
B. MEK
C. STAT
D. Elk-1
C. STAT
In the cyclic AMP second messenger pathway, which of the following degrades cAMP?
A. Phosphodiesterase
B. Diacyl-glycerol
C. Arrestins
D. Protein kinase A
A. Phosphodiesterase
Estrogen is synthesized from:
Cholesterol
What are the names of the non-steroid receptors that bind to intracellular receptors?
- Thyroid hormone: Synthesized from tyrosine
- Vitamin D3
- Retinoids
Review Figure 3-1
Review figure 3-2
What are the negative and positive feedback loops?
Which of the following is not a messenger that binds to the cell surface receptors?
A. Glutamate
B. Aspartate
C. Glycine
D. GABA
E. Arginine
E. Arginine
Note that neurotransmitters are (hydrophilic or hydrophobic) and can only bind to
membrane ________.
hydrophilic, receptors
Which of the following is a Indoleamine?
A. Serotonin
B. Dopamine
C. Noepinephrine
D. Epinephrine
A. Serotonin
Many neurotransmitter receptors are ______-gated ion
channels.
ligand
Binding of growth factors to extracellular domains results in….
phosphorylation of both the receptors and the intracellular
target proteins that propagate the signal.
- First step is ligand-induced receptor dimerization.
- Leads to receptor autophosphorylation.
• All receptors for G proteins are ___-membrane-spanning α helices:
7
What is special about 7? One end sticking out
Which subunit of the G protein is the most variable (more than 20 types) and is specific
for a particular G protein.
α subunit
- α subunit binds GDP when inactivated.
- Activation results in the exchange of GDP to GTP.
- The β and γ subunits form a dimer.
Effectors associated with G proteins include:
- Adenyl cyclase
- Phospholipases
- Ion channels
Categories of G proteins\
- GS
- Gi
- Gt/g
- Go
- Gq
• GS
• Stimulates activity of adenyl cyclase
• Gi
• Inhibits activity of adenyl cyclase
• Gt/g
• Stimulates breakdown of GMP in photoreceptors and taste
receptors.
• Go
• Opens calcium channels in neurons.
• Gq
• Activates phospholipases which increases activity of IP3.
