Cell signaling

Question 1

Ligand definition

Answer 1

general term for a molecule that binds to a specific site on a protein

Question 2

receptor definition

Answer 2

protein that recognizes and respons to a signaling molecule - ligand; signal transduction

Question 3

Agonist definiton

Answer 3

substance (ligand) that interacts with a receptor to initiate a physiological response

Question 4

Antagonist defitition

Answer 4

Substance (ligand) that interferes with or inhibits the physiological action of another substance

Question 5

second messenger

Answer 5

small intracellular signaling molecule generated or liberated in response to an extracellular signal

Question 6

What can signaling molecules exhibit for a lock and key model?

Answer 6

signaling molecules exhibit some 3d structure that is complimentary to the receptor binding site

Question 7

What does an interaction of an agonist with the binding site induce?

Answer 7

interactions of an agonist with the binding site induces a conformational shift of the receptor to a form that affects cell function

Question 8

What can antagonists exhibit?

Answer 8

they may exhibit structural complementarity to the binding site or may interact with a different site to change receptor structure and render the receptor unresponsive to an antagonist

Question 9

cell coupling is between

Answer 9

signaling molecules and gap junctions

Question 10

contact-dependent is b/w?

Answer 10

signaling molecule and receptor

Question 11

secreted molecules is b/w

Answer 11

signaling molecules and receptor

Question 12

Cell coupling example - glucagon receptors
signal?
function?

Answer 12

glucagon receptors are not uniformly distributed on cells throughout the liver.
Signal - cAMP
Function - synchronize response to glucagon

Question 13

Cell coupling example - cardiac muscle cells
signal?
function?

Answer 13

cardiac muscle cells are electrically coupled.
Signal - electrical conductance
function - synchronization of cardiac muscle contraction

Question 14

Gap junction structure
6___=_____
2___= 1____
Groups of ____ = ___

Answer 14

connexin
group of 6 connexin = 1 connexon
2 connexons = 1 gap junction
groups of gap junction = plaque

Question 15

contact-dependent signaling leukocyte example?
signal?
Receptor?
function?

Answer 15

leukocyte adhesion prior to transmigration
signal - glycoproteins on leukocytes
receptor - adhesion proteins on endothelial cells
function - attract and guide leukocytes to a site of injury

Question 16

Contact-dependent synapse example?
Signal?
Receptor?
Function?

Answer 16

synapse formation and maintenance
signal - B-neurexin on presynaptic terminus
Receptor - neuroligin on postsynaptic cell
Function - guide and maintain synaptic proteins in close function proximity

Question 17

Neutrophil Extravasation

PGSL1?

Answer 17

P-selectin glycoprotein 1: receptor for P-selectin

Question 18

Neutrophil Extravasation

P-selectin

Answer 18

a cell adhesion molecule expressed in inflamation. Interaction of PGSL-1 with P-selectin on an adhered platelets leads to loose association and leukocyte rolling

Question 19

Neutrophil Extravasation

integrins

Answer 19

obligate dimers of one alpha and one beta integrin. CD11 is alpha and CD18 is beta

Question 20

Neutrophil Extravasation

ICAM-1

Answer 20

intracellular adhesion molecule 1 - a cell surface glycoprotein that binds to integrins

Question 21

Neutrophil Extravasation

PECAM-1

Answer 21

platelet endothelial cell adhesion molecule involved in leukocyte transmigration

Question 22

B-neurexin

Answer 22

(presynaptic) interacts with neuroligan (postsynpatic)

Question 23

Presynaptic scaffolding includes?

Answer 23

CASK (kinase) and MINT (adaptor) which allow for regulated and physical interactions with other members of presynpatic complex including voltage-sensitive calcium channels and SNARE proteins

Question 24

Post synaptic scaffolding includes?

Answer 24

postsynaptic density protein which physically interacts with neurotransmitter receptors to hold them in close proximity to the release site.

Question 25

Secreted molecules - hormones | signal, receptor, function

Answer 25

hormones signal - vasopressin receptor - vasopressin receptor function - fluid balance

Question 26

Secreted molecules - neurotransmitters: signal, receptor, function

Answer 26

signal - acetylcholine Receptor - nicotinic acetylcholine receptor Function - muscle contraction

Question 27

Secreted molecule - autocoids | Signal, receptor, function

Answer 27

signal - bradykinin receptor - bradykinin receptor function - vasodilation

Question 28

secreted molecule - cytokines; signal, receptor, function

Answer 28

``` signal - interleukin 2 receptor - interleukin receptor function - immune system ```

Question 29

Signaling via secreted molecules: | Endocrine, neuroendocrine, paracrine, autocrine

Answer 29

Endocrine - signaling molecule is transported via vascular circulation Neuroendocrine - like endocrine with signaling cell being a neuron Paracine - signaling molecule diffuses through extracellular medium to nearby cell Autocrine signaling molecule diffuses through extracellular medium; signaling cell is also targeted

Question 30

Neuroendocrine signaling example - vasopressin or antiduretic hormone Signal, receptors, functions

Answer 30

Signal - arginine vasopressin receptor - VR1 on vascular smooth muscle cells or VR2 on kidney collecting duct cells functions - increase vascular resistance and BP, increase water retention to maintain vascular volume

Question 31

Vasopressin signaling condition

Answer 31

elevated blood osmolality or low blood volume

Question 32

vasopressin signaling condition and event of hypothalamic cells do what?

Answer 32

hypothalamic neurosecretory cells respond by releasing vasopressin in posterior pituitary which enters vascular circulation

Question 33

Vasopresssin signaling V1 receptors on smooth muscle cells activation causes

Answer 33

cytosolic release of DAG and IP3 which causes contraction

Question 34

Vasopressin signaling V2 receptors in nephrons activation causes

Answer 34

increase cytosolic cAMP which induces the insertion of aquaporins allowing water retention

Question 35

Vasopressin signaling outcome

Answer 35

increase BP and stabilize fluid volume/reduce fluid loss

Question 36

Paracrine signaling - histidine induced vascular changes signals? receptors? functions?

Answer 36

signal - histamine and nitric oxide receptors - H1 on vascular endothelial cells; smooth muscle guanylyl cyclase functions - vasodilation as a component of an inflammatory response

Question 37

Neuronal signaling neuromuscular junction - signal, receptor, functions

Answer 37

signal - acetylcholine receptor - nicotinic acetylcholine receptor functions - voluntary muscle contraction

Question 38

nAchR activation leads to?

Answer 38

membrane depolarization, increase cytosolic calcium and muscle contracton

Question 39

Endocrine vs synpatic signaling Signal reached? Concentrations?

Answer 39

endocrine - signal reaches most synaptic - signal reaches selected cells Endocrine - low concentrations of signaling molecules are required to activate target Synaptic - high concentrations of signaling molecules required to activate target

Question 40

Cell surface receptors vasopressin or ADH signal, receptor, functions

Answer 40

Signal - arginine vasopressin receptors - VR1 on vascular smooth muscle cells VR2 on kidney collecting duct cells functions - increase vascular resistance and BP and increase water retention to maintain retain vascular volume

Question 41

Intracellular/nuclear receptors - aldosterone regulation of electrolyte concentrations signal? receptor? function?

Answer 41

signal - aldosterone (steroid hormone) receptors - mineralcorticoid (aldosterone) receptor functions - enhance K+ secretion and Na+ retention by kidney

Question 42

In renal collecting duct cells, aldosterone induces?

Answer 42

Aldosterone induces SGK1 expression which modulates K+ and Na+ channel activity and turnover, results in net K+ secretion along with Na+ and water retention

Question 43

Intracellular enzymes - nitric oxide to induce vasodilation example signal, target, functions?

Answer 43

signal - NO target - guanylyl cyclase function - vasodilation accompanying inflammation

Question 44

Cell to cell signaling summary: occurs? can be targeted based on? ______dependent (2 things)

Answer 44

occurs through a variety of modalities. Can be targeted based on - location of signal release; location of receptor; mechanism of distribution; receptor subtype. Concentration and solubility dependent. can be manifested over a variety of time frames.