Previously

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Previously
Previously in Cell Bio
A) Fluid Mosaic Model
B) Cell Organelles
C) Introduction to first case study
Today
Extracellular signaling Types, receptors
involved, Roles in Graves disease
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Thyroid activators
How are they all coordinated?
Our Case Study ? Thyroid stimulation Extracellula
r signaling and the receptors that mediate it
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Signaling types
Types of Extracellular Signaling

• Up close
• Direct contact

PM receptors Gap junctions Secreted ECM

• Autocrine

• Through space
• Paracrine
• Endocrine
• Synaptic

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Compare
Compare synaptic signaling endocrine signaling
Carried how?
Relative rate
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Binding vs. Effector Specificity

• Ex. Increase in circulating thyroid hormone
  causes
• Increase in secretion by sweat glands
• Increase in rate and force of heart
  contractions
• Decrease in muscle strength

How can this happen?
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Binding vs. effector specificity 2
How can thyroid hormone cause different
responses in different parts of the body?
Ligand needs to bind with receptor
Different cells make different receptors
Same receptor/ligand complex may trigger
different response in a different cell type
(Receptors and Ligands? What are they?)
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Receptor characteristics
Characteristics of a receptor
Ribbon diagram of Thyroid hormone bound to
Thyroid hormone receptor
Diagram of isoproterenol bound to B2 adrengergic
receptor (Fig20-1 Molecular Cell Biology)
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Types
Types of Receptors
G-protein linked receptors (G protein coupled
receptors/GPCR)
Ion Channel receptors
Enzyme linked receptors (Receptor S/T kinases,
Receptor Y kinases Receptor guanylyl cyclases,
Protein Y phosphatases, Y-kinase associated
receptors H-kinase associated receptors)
Intracellular receptors
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What types in thyroid regulation?
Normal thyroid function
Endocrine signaling (Intracellular receptor for
T4)
Endocrine signaling PM receptor
Negative feedback loop What is it and why is it
important?
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What happens in Graves?
Whats different in a Graves disease
patient? (hyperthyroidismincreased thyroid
function)
Patients have increased T3 and T4 in bloodstream
What might make a thyroid put in overtime?
HYPOTHESES?
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Hypothesis Thyroid being over-stimulated
Normal stimulation results from
TSH/receptor interaction How does the thyroid
know to react? How does a receptor provide
specificity
Hypothesis Mutation in signaling within cell
leading increase in thyroid hormone production
Normal activation is the result of signal
transduction second messenger cascade How does
signal transduction work? What could have gone
wrong?