IB Biology Topic C2.1.9: Transmembrane Receptors That Activate G Proteins Notes

GPCRs Convert an Outside Signal Into an Inside Response Using a G Protein Switch

G protein-coupled receptors (GPCRs) are transmembrane receptors in the plasma membrane.

They are called G protein-coupled because they work with a G protein, a molecular switch that relays the signal inside the cell.

Definition

G protein-coupled receptors

A large family of transmembrane receptors that detect external signals and activate intracellular G proteins, initiating cellular responses.

Structure of a GPCR

Seven-pass helix

A single chain crosses the membrane seven times as seven alpha-helices.

Ligand-binding site

It sits on the extracellular side, where the signalling molecule binds.

Intracellular domain

It faces the cytoplasm and contacts the G protein to pass the signal on.

Analogy

Think of a GPCR as a doorbell.
The ligand presses the button, the receptor is the bell, and the G protein is the wiring that carries the signal to the chime inside the house.

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Tip

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Tip

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Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
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IB Biology Topic C2.1.9: Transmembrane Receptors That Activate G Proteins Notes

GPCRs Convert an Outside Signal Into an Inside Response Using a G Protein Switch

Structure of a GPCR

Ligand Binding Triggers a GDP-to-GTP Swap That Sends the Signal Onward

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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GPCRs Convert an Outside Signal Into an Inside Response Using a G Protein Switch

Structure of a GPCR

Ligand Binding Triggers a GDP-to-GTP Swap That Sends the Signal Onward

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic C2.1.9: Transmembrane Receptors That Activate G Proteins Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

GPCRs Convert an Outside Signal Into an Inside Response Using a G Protein Switch

Structure of a GPCR

Ligand Binding Triggers a GDP-to-GTP Swap That Sends the Signal Onward

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

GPCRs Convert an Outside Signal Into an Inside Response Using a G Protein Switch

Structure of a GPCR

Ligand Binding Triggers a GDP-to-GTP Swap That Sends the Signal Onward

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account