Biotechnology Major, Signaling Pathways for G Protein Coupled Receptors?

The main pathways of G-protein-coupled receptor signal transduction include: biogenic amine hormones--- epinephrine, norepinephrine, histamine, serotonin; peptide hormones--- bradykinin, luteinizing hormone, parathyroid hormone; Odor molecules and light quanta.

Depending on the effector enzyme and the component of the intracellular second messenger signal transduction, there are two main reaction pathways:

1) Receptor-G protein-AC pathway:

Hormones are the first messengers --- corresponding receptors, which are coupled to G-protein ---to activate intramembrane adenylyl cyclase (AC)--Mg2+--ATP--- cyclic adenosine monophosphate (CAMP second messenger)--CAMP-dependent protein kinase (PKA)--catalyze the phosphorylation of a variety of substrates in cells--- biological effects (such as cell secretion, muscle cell contraction, cell membrane permeability changes, and various enzymatic reactions in cells).

2) Receptor-G protein PLC pathway:

--- membrane receptors such as insulin, oxytocin, prolactin, and hypothalamic regulatory peptide bind--- and are activated by G protein--- an intramembrane effector enzyme, phospholipase C (PLC), which breaks down inositol diphosphate (PIP2) to produce inositol triphosphate (IP3) and diacylglycerol (DG). IP3 and DG act as second messengers and play a role in information transmission within the cell.

IP3- binds to Ca2+ channels on the outer membrane of endoplasmic reticulum --- releases Ca2+ into the cytoplasm--- the concentration of Ca2+ in the cytoplasm increases significantly--- Ca2+ binds to intracellular calmodulin (CAM), activates protein kinase, promotes protease phosphorylation, and thus regulates cellular functional activities.

The role of DG is primarily to specifically activate protein kinase C (PKC). Like PKA, PKC can phosphorylation a variety of proteins or enzymes, thereby regulating the biological effects of cells.

It is advisable to buy a copy of Cell Biology with a detailed process.

Directly below is a PKA PKC activation creb pathway, camp-PKA pathway can activate the nucleus CREB This is clear, and the others...

This teacher didn't talk about it in class.

The most abundant and important signal transduction pathway on the cytoplasmic membrane is G-protein-mediated signal transduction. This signal transduction pathway has two important features:

The system consists of three parts: a receptor for 7 transmembranes, a G protein, and an effector (enzyme);

Spawn a second messenger.

RS and RI are located on the outer surface of the plasma membrane and recognize and bind to extracellular signaling molecules, and the receptor has two regions, one acting with hormones and the other with G proteins.

The G protein, also known as coupling protein or signal-converting protein, couples the receptor to adenylyl cyclase to convert extracellular signals across the membrane into intracellular signals, the second messenger camp.

A brief description of the G-protein-coupled receptor-mediated signaling pathway.

Correct Answer: G protein is short for trimeric GTP-binding regulatory protein, which is located on the cytoplasmic side of the plasma membrane and consists of three subunits: G, G, and G, G exist in the form of dimers, and the G and G subunits are anchored to the plasma membrane by covalently bound lipid molecules, respectively. The G subbasic itself has GTPASE activity and is a molecularly switched protein.

When the ligand binds to the receptor, the trimeric G protein dissociates, and the exchange of GDP and GTP occurs, and the free G-GTP is in the activated state, resulting in binding and activation of the effector protein, thereby transmitting signals; When G-GTP is hydrolyzed into G-GDP, it is in an inactivated shutdown state, terminating signaling and leading to the reassembly of the trimeric G protein, and the recovery system enters a resting state. At present, the well-known G protein-coupled receptor signaling pathways are: CAMP signaling pathway and phosphatidylinositol signaling pathway.

CAMP is produced by the hydrolysis of ATP in cells by adenylyl cyclase (AC), which in turn binds to protein kinase A (PKA) to initiate a series of cytoplasmic reactions and effects in the nucleus. In the phosphatidylinositol signaling pathway, the effector phospholipase (PLC) decomposes phosphatidylinositol 4,5-bisphosphate on the membrane into two messengers: diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3), IP3 mobilizes the intracellular calcium pool to release Ca2+, which binds to calmodulin to cause a series reaction, and DAG activates protein kinase C (PKC) under the synergy of Ca2+, which then causes a cascade reaction.

Structure and activation of G protein-coupled receptors.

Process: The ligand binds to the receptor and activates, the receptor binds to the GA subunit, and the activation of the receptor changes the G A subunit, resulting in the dissociation of GDP from G protein, and GTP binds to the GA subunit, triggering the dissociation of the GA subunit from G and the receptor, the dissociation of the ligand-receptor complex, and the binding and activation effect of the GA subunit. The hydrolysis of protein GTP to GDP triggers the separation of the G A subunit from the effector protein and rebinds to the G subunit, returning to the resting state of the trimeric G protein.

The intracellular part has a G protein-binding region. G protein, a trimer composed of three subunits, binds to GDP in the resting state When the receptor is activated, the GDP complex is exchanged with GTP in the cytosol with the participation of Mg2+, and GTP is separated from and activates the effector protein, while the ligand is separated from the receptor. The subunit itself has GTPase activity, which promotes the hydrolysis of GTP into GDP, and returns to its original resting state after forming G protein trimers with the subunit.

G protein-coupled receptor-mediated signaling pathway:

The intracellular part has a G protein-binding region. G protein, a trimer composed of three subunits, binds to GDP in the resting state When the receptor is activated, the GDP complex is exchanged with GTP in the cytosol with the participation of Mg2+, and GTP is separated from and activates the effector protein, while the ligand is separated from the receptor.

The subunit itself has GTPase activity, which promotes the hydrolysis of GTP into GDP, and returns to its original resting state after forming G protein trimers with the subunit.

Structural features of G protein-coupled receptors:

G protein-coupled receptors are all intrinsic membrane proteins, and each receptor contains a transmembrane domain composed of seven helices, which divide the receptor into N-terminus, C-terminus, 3 loops and 3 loops. The extramembrane portion of the receptor is often modified with glycosylation.

The extramembrane ring contains two highly conserved cysteine residues that can stabilize the spatial structure of the receptor by forming disulfide bonds. Some light-sensitive channel proteins (ChannelRhodopsin) have a similar structure to G protein-coupled receptors and also contain seven transmembrane helices, but also contain a transmembrane channel for ions to pass through.

The auriculated structure of the glutinous aura-coupled receptor is characterized by transmembrane () times. Times.

Times. Times. Times. Correct answer: D

Answer]: The test point of this question is the type of receptor, and what does not belong to G protein-coupled receptors is the -aminobutyric acid (GABA) receptor, which belongs to ion channel receptors. Ion channel receptor dispensers, gated ion channels, and voltage-gated ion channels.

Including the revision of N-type acetylcholine sensitization group, -ammonia bridge orange butyric acid (GABA) receptor, etc.