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Physiology > Receptor Physiology And Signalling > Flashcards

Receptor Physiology And Signalling Flashcards

1
Q

Changes in a cell’s membrane potential (seen in gap junction between cells where ions are passing through protein connection between cells)

A

Electrical signal

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2
Q

Molecules secreted by cells into extracellular fluid; responsible for the majority of activities within the body (seen in secretion of a neurotransmitter that binds to a receptor protein)?

A

Chemical signals

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3
Q

Characteristic of Signalling Pathways

A

Multiple, hierarchical steps
Amplification of the hormone-receptor binding event, magnifying the response
Activation of multiple pathways and regulation of multiple cellular functions
Antagonism and regulatory control

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4
Q

Relay of a message from the sender cell to a receiver cell to initiate a cascade of events

A

Transduction

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5
Q

Signal molecule that binds to a receptor

First messenger: brings info to target cells

A

Ligand

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6
Q

Response of cells

A 
Altered ion transport
Altered metabolism
Altered gene expression 
Altered cell shape or movement
Altered cell growth and division
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7
Q

Secondary messengers and serve as the amplification steps

A

Intracellular signalling proteins

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8
Q

Local Cell Communication

important during development and in immune responses

A

Contact-dependent signals
Membrane-associated ligands

Communication Junctions (Direct interactions)
gap, adhering, tight

Chemical signals
autocrine, paracrine

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9
Q

Ligands on the cell membrane of one cell bind to the receptors on the cell membrane or target cell

Provide spatial clues in migrating cell

A

Contact-dependent signals

Membrane-associated ligands

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10
Q

Link direct cytoplasm of two adjacent cells

Fastest way of cell-to-cell communication

Allows exchange of ions, secondary messengers and metabolites

Allows cells to be electronically coupled which is important for activity of CARDIAC and SMOOTH MUSCLE cells

Made up of proteins which can be opened or closed called

A

Gap junctions

Connexins

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11
Q

Have transmembrane proteins that link with the adjacent cell through the actin filaments in cytoskeleton

Maintenance of normal cell structure

Serve as a signalling role during organ development and remodelling

A

Cadherin

Adhering junctions

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12
Q

Consists of a network of proteins

Limit the passage of cell molecules and ions through the space between the cell

A

Claudins

Tight junctions

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13
Q

Diffuses molecukes through ECF to act on nearby cell

A

Chemical signals

Autocrine - sender and receiving cell is same cell; development where cells reinforce their identities

Paracrine - released by one type of cell and diffused to receptors of adjacent cells or cells in proximity via ECF; does not get into the blood

ex. Fibroblast growth factor FGF

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14
Q

Long distance communication

A

Synaptic transmission
Endocrine
Neuroendocrine

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15
Q

Binds to extracellular domains
SLOW response

Peptided, Amino acids

A

Polar Lipophobic ligands

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16
Q

Diffuse through phospholipid bilayer
RAPID response due to AMPLIFICATION STEP

Steroid, thyroid hormone, Vit A and D

A

Nonpolar ligands Lipophilic

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17
Q

Ionotropic receptors

Conformational change happens to the channels when the ligand binds with the receptor -> opening of the channels to allow the passage of ions

The ligand that binds to the cell changes the cell’s polarization and activates the ion channels directly and rapidly

Ex. Acetylcholine

A

Ligand-gated ion channel

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18
Q

7 transmembrane domain receptors
Serpentine receptors

An integral protein that crosses the cellular membrane 7 times

Physiologic response is mediated by G proteins of GTP binding protein family

A

G-protein Receptors

19
Q

In the absence of the ligand, G proteins are inactive and form a heterotromeric complex (GDP+ alpha subunit)

Upon ligand binding to the inactive GPCR, conformational change in the G protein that promotes the release of GDP now (GTP +alpha subunit)

GDP-GTP exchange stimulated dissociation of the complex from the receptor, disassembly of trimer into free alpha subunit and beta,gamma complex

GTP-bound alpha subunit now interact in the plane of membrane with downstream effectors such as adenylate cyclase and phospholipase

Beta, gamma subunit can now activate ion channels or other effectors

A

GPCR Mechanism

20
Q

Hydrolysis of GTP to GDP and inorganic phosphate by GTPase INACTIVATES the signalling events of alpha subunit -> inactive alpha-GDP complex that dissociates from its downstream effector and reassociate with beta, gamma subunit

GTPase activity is enhanced by Regulation of G Protein Signalling family of proteins as long as ligand is attached, it will continue to activate G protein

A

GPCR Mechanism

21
Q

G PROTEIN Signalling Pathways

A 
Adenylyl cyclase
Phosphodiesterase
Phospholipase 
Ca - directly stimulated through Gs 
Protein phosphatase
B gamma
Monomeric G protein - GTP binding protein
22
Q

Alpha subunit binds to this

Converts ATP into cAMP

cAMP then open ion channels or activate PKA (Protein Kinase A) which regulates the effector protein activity

ai inhibitory, adenylate cyclase not activated

ex: L type calcium channel

A

Adenylate cyclase

23
Q

Found in cytoplasm and helps in muscle contraction

Activated by cAMP to open Ca channels

A

Calmodulin

24
Q

Used in phototransduction or light perception

Ligand = light or proton

Activated by Gi (G protein with alpha subunit)

Light interacts with the receptor coupled to at (transducin)
Activates phosphodiesterase
Breaks down cAMP back into GMP
Leads to the closure of cGMP - dependent channels

A

Phosphodiesterase

25
Q

Acts on phospholipids in plasma membrane

Products:

DAG - activates Protein Kinase C
IP3 - promotes increase of Ca in the cell

A

Phospholipase

26
Q

Cuts bond at carbon 1

Results to free fatty acid and DAG

A

Phospholipase A1

27
Q

Cuts at carbon 2
Activated by Gi or Go

Results to arachidonic acid and stay within the cell or be converted to eicosanoids

A

Phospholipase A2

28
Q

Cuts at carbon 3
Activated by Gq

Results to hydrolysis of Phosphatidylinositol 4,5 diphosphate into Inositol Triphosphate (IP3) and DAG

A

Phospholipase C

29
Q

Cuts phosphodiester bond

Results to free headgroup and Phosphatic acid

A

Phospholipase D

30
Q

Reverses action of kinases

Dephosphorylates the proteins phosphorylated by PKA

A

Protein phosphatase

31
Q

Actin cytoskeleton, cell cycle progression, gene expression

A

Rho

32
Q

Transport of RNA and Proteins

A

Ran

33
Q

Gene expression, cell growth, associated with oncogenes

A

Ras

34
Q

Glucagon
B adrenergics

Effector

A

Inc adenylyl cyclase

Gluconeogenesis, lipolysis, glycogenolysis

35
Q

Odorant

A

Inc adenyly cyclase

36
Q

Acetylcholine

Alpha 2 adrenergics

A

Decrease adenyly cyclase
Inc Potassium channels

Slowed heart rate

37
Q

M2 cholinergics

A

Dec Ca channels

38
Q

Secondary messengers

A 
cAMP AND cGMP
IP3 and DAG
Ca 
Arachidonic acid and metabolites
HETE
ETE
39
Q

Function directly as enzymes when activated or are closely associated with the enzymes they activate

A

Catalytic Enzyme Coupled Receptors

40
Q

Ligand binds to receptor
Receptor directly converts GTP to cGMP

Receptors that mediate cellular responses to ANP and NO

A

Recetor Guanylyl Cyclase

41
Q

Intracelljlar domain is a serine/threonine kinase that phosphorylates proteins containing serine/threonine amino acids

Like TGFB fibrosis

A

Receptor Serine/Threonine Kinase

42
Q

Phosphorylates tyrosine residues on themselves to become fully active to allow the phosphorylation of other proteins

Ex. EGF, PDGF
Insulin, Mitogenesis, Protein synthesis, Glycogen synthesis, Glucose transport

A

Receptor Tyrosine Kinase

43
Q

the JAK is the catalytic part instead of receptor itself

Cytokine receptors consist of at least 2 chains: Janus kinase and cytoplasmic domains

One phosphorylates the other dephosphorylates is found on cytoplasmic areas

A

Tyrosine-Kinase Associated Receptors TKAR

44
Q

Receptors located in cytoplasm and in the nucleus

Bind to specific DNA sequences hormone response elements in regulatory region of responsive genes

Steroid hormone, thyroid hormone, aldosterone

A

Intracellular Nuclear Receptors

Physiology (23 decks)

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