Chapter 11
11.2- Reception
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Ligand is highly specific
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There will be a shape change in a receptor
·
Most signal proteins are plasma membrane
proteins
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3 Receptor in plasm a membrane
o
G-Protein- coupled
o
Receptor tyrosine kinases
o
Ion channel receptors
·
G protein- coupled receptors (GPCR)
o
Largest family
o
Works with help of a G protein
o
G protein acts as an on/off switch- if GDP is
bound to the G protein, the G protein is inactive
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Receptor tyrosine kinases (RTKs)
o
Attach phosphates to tyrosine
o
Can trigger multiple signal transduction pathways
at once
o
Abnormal functioning is associated with cancers
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Ligand- gated ion channel
o
Acts as a gate when receptor changes shape
o
When a signal molecules binds as a ligand to the
receptor, the gate allows specific ions, such as NA+ or CA+,
through a channel in the receptor
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Intracellular Receptor
o
Found in the cytosol or nucleus of target cells
o
Small or hydrophobic chemical messengers
§
Activate receptors
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EX: Steroid/ Thyroid hormone
o
An activated hormone receptor complex can act as
a transcription factor, turning on specific genes
