cell communication Flashcards
most common control system (feedback loop) for maintaining homeostasis
negative feedback loop
example of endocrine cell signaling
adrenal medulla releases epinephrine that binds to B1 receptors on heart
example of autocrine cell signaling
NE binding to presynaptic A2 receptor on save nerve terminal that released NE.
neurotransmitter signaling is a specific type of which form of cellular communication?
paracrine signaling
example of a receptor that performs compartmentalization
ryanodine receptor (Ryr) is a scaffolding protein. multiple components of signaling pathways come together on scaffolding proteins to increase their concentrations and effects
calcium channels do this as well
general flow through GPCR
first messenger (ligand) –> receptor –> effector –> second messenger –> cellular response
name 3 chemical messengers derived from arachidonic acid (these are all lipophilic)
prostaglandins
leukotrienes
thromboxanes (eicosanoids. ex: anandamide)
chemical messengers derived from tyrosine (4)
dopamine
NE
epi
iodothyronines
characteristics of steroid chemical messengers
derived from:
where they bind on target cells:
storage:
how they circulate in the blood:
derived from cholesterol
circulate in blood bound to a protein
bind to receptors in cytoplasm or nucleus of target cells
not stored in producing cells
characteristics of eicosanoid chemical messengers
derived from
primarily what kind of actions
how they bind to the cell
storage
precursor
derived from polyunsaturated fatty acids
arachidonic acid is main precursor
primarily autocrine and paracrine actions
unlike steroids, they usually bind to cell surface receptors
not stored in producing cells
which category of signaling molecules are stored in vesicles in the cells that synthesize the molecule (2)
hydrophilic messengers
peptide and protein messengers
opioid peptides include (6)
beta endorphins
dynorphins
enkephalins
substance P
calcitonin gene related peptide (CGRP)
orexins
hydrophilic chemical messengers include (4)
amino acids (glycine, glutamate, gaba, aspartate)
biogenic amines (DA, NE, epi, serotonin, histamine)
choline esters (Ach)
iodothyroxines (T4, T3)
lipophilic chemical messengers include (4, 2 have examples)
steroids (aldosterone, cortisol, testosterone, progesterone, estrogens)
eicosanoids (prostaglandins, leukotrienes, thromboxanes)
VitD, retinoids
how to G proteins turn off
GTPase activity in alpha subunit. catalyzes hydrolysis of GTP to GDP and Pi.
alpha subunit dissociates with effector and goes back to by subunit
what is bound to the alpha subunit of a GPCR when its in the off/inactive state
GDP
what is bound to the alpha subunit of a GPCR when a ligand has attached to the GPCR and it is turned “on” or in the active state
GTP
in the GPCR, what does the GDP GTP exchange do to the aby complex (after activation)
aby complex disassembles into GTP bound alpha subunit and separate by complex
in the activated GPCR, the alpha GTP subunit will interact with effectors that include either
adenylate cyclases (AC)
phospholipase C (PLC)
phospholipase A2 (PLA2)
in the activated GPCR, the by complex subunit will interact with effectors that include either
Gi-0 regulated potassium channels (GIRK)
VgCa2+ channels
B adrenergic receptor kinase (BARK)
heterotrimeric G proteins are classified into 4 families based on nature of alpha subunit (and what they stimulate/inhibit)
Gs (stimulates adenylate cyclase)
Gi, 0 (inhibits adenylate cyclase)
Gq, 11 (activates PLC)
G12, 13 (activates small G proteins)
activated GPCR alpha subunits target these 3 big down stream effectors (and know their second messengers)
adenylyl cyclase (AC) –> cyclic adenosine monophosphatate (cAMP)
phospholipase C (PLC) –> inositol triphosphate (IT3) and diacylglycerol (DAG)
phospholipase A2 (PLC2) –> eicosanoids (20 carbon lipid mediators)
adenylyl cyclase function, inbhibition and stimulation
AC converts ATP to cAMP
Gs stimulates cAMP while Gi inhibits cAMP
PLC function and stimulation
PLC converts PIP2 to IP3 and DAG (both second messengers)
Gq11 with Ca2+ activates PLC