Lecture 14 Membrane Protein Functions Flashcards
How does the structure of a membrane protein affect its function?
It is crucial for moving ions, molecules, or transmitting signals across the membrane.
What are the main steps of a signal transduction cascade?
Signal molecule binding
Reception by a membrane receptor
Relay via intracellular secondary messengers
Amplification, transduction, and response
Signal termination
how many segments do G-Protein-Coupled Receptors have?
7
what do G-Protein-Coupled Receptors release after a change in conformation?
G-proteins
what type of ligands do G-Protein-Coupled Receptors bind to?
serotonin, epinephrine, dopamine
How do non-covalent interactions affect binding affinity?
influence how strongly molecules bind.
What does a low 𝐾𝑑 value indicate?
It indicates stronger binding between molecules.
What happens when the β2-adrenergic receptor is activated?
TM6 shifts 14 Å, releasing Gα-GTP, activating adenylyl cyclase, and producing cAMP.
How is epinephrine signalling turned off effectively?
cAMP breakdown
GTP hydrolysis
Epinephrine unbinding
What is the function of Ras proteins?
They bind and hydrolyze GTP to regulate cell proliferation and apoptosis.
How do enzyme-linked receptors transmit signals?
phosphorylation occurs through tyrosine kinases, activating intracellular pathways.
What are the two competing hormones discussed?
Insulin and epinephrine, which can regulate each other’s signaling pathways.
What types of molecules can cross the membrane through passive diffusion?
Small, uncharged, or lipophilic molecules, such as oxygen and water.
What makes facilitated diffusion saturable?
the availability of binding sites on the membrane proteins.
What is the role of potassium ion channels?
They regulate cell volume, hormone secretion, and electrical impulse formation in neurons.
