Cell Signalling Flashcards
Hydrophilic signalling is done by signal molecules binding to receptors on the
Cells surface
Hydrophobic signalling is done by signal molecules binding to the receptor by
Diffusing through the membrane
Contact signalling occurs through membrane bound proteins such as
Integrins. And gap junctions
Paracrine signalling is when a cell releases a chemical signal that effects
Nearby cells
Autocrine signalling occurs similarly to _______except the chemical signal released effects
Paracrine; itself
Endocrine signalling occurs when the signal that is released must________ to reach its desired cell
Travels long distance
Synaptic signalling occurs when the chemical signal travels_______ to affect electrical signalling in adjacent cells
Short distances
(Axons)
Specific Ligands only act on specific cells. T/F
False
A specific ligand can act on multiple cells for multiple different functions
A common ligand with multiple receptors with different functions is
Acetylcholine
Transmembrane receptor mechanisms include
G protein coupled receptors
Enzyme coupled receptors
Ion channel coupled receptors
Intracellular receptors
Intracellular receptors refer to receptors located on the
Nucleus
Intracellular receptors receive ligands through what signalling
Hydrophobic
Agonists cause a conformational change on the receptor resulting in the ______of the receptor
Activation
Antagonist bind the receptor and are synonymous to
Competitive Inhibitors blocking the active site and preventing activation
Inverse agonists bind the receptor and
Stabilizes the inactive state, can reduce the the activity
Intracellular receptors bind to
Hydrophobic ligands
Intracellular receptors are also called
Nuclear hormone the family
OR
steroid hormone family
Intracellular receptors are primarily________which modifies gene transcription
Transcription factors
Hormone receptor ligands are made from
Cholesterol
Class I nuclear receptors exist in the________which are pre bound to_______. Once binded, the receptor is dimerized and them translocated to the_______
Cytosol; HSP90; nucleus
Class II nuclear receptors pre exist already bound to______. Ligand binding the causes the release of______ and ______ proteins
DNA; Co-repressors; co-activator
The difference between class I and Class II nuclear receptors is that
Class I receptors must bind to the ligand first and THEN translocate to DNA
class II receptors already exist on the DNA and simply await the ligand for binding
Nuclear hormones are typically
Hydrophobic
G proteins are composed of how many units? What are they?
3 units
Alpha, beta, and gamma units
G proteins are inactivated when bound to_______and activated when bound to________
GDP; GTP
Alpha G protein when bound to GTP activated which enzyme
Adenylate cyclase
The function of adenylate cyclase is to
Convert ATP to cAMP
cAMP acts as a_______after the hormone
Second messenger
cAMP binds and activates
Protein Kinase A (PKA)
PKA phosphorylates
GLycogen phosphorylase kinase
Glycogen phosphorylase kinase activates_______which degrades glycogen into glucose
Glycogen phosphorylase
Glycogen phosphorylase, and glycogen phosphorylase kinase are inactivated by which hormone
Insulin
Another ‘second messenger’ can also be
Calcium
G protein coupled receptors (GPCRS) take a similar shape as
7-transmembrane alpha helices
GTP hydrolysis leads to
Inactivation of the G protein
Trimeric G proteins have an intrinsic_______which hydrolases GTP to GDP
GtpAse
GTP binding to the alpha subunit causes _______from the beta and gamma subunits
Separation
Small G-proteins do not have an intrinsic_________and the hydrolysis of GTP must be supplied by
GTPase; GAP (GTPAse accelerating protein)
cAMP/PKA mechanism ONLY target glucose phosphorylase kinase and glucose phosphorylase. T/F
False
They have many potential targets
cAMP/PKA targets phosphorylation of _______to regulate gene expression
CREB
GCPRS can induce responses other than elevating cAMP. T/F
True
Some G proteins such as______proteins can inhibit adenylate cyclase by binding with_______
Gi; alpha adrenergic receptors
The function of GPCR kinase (GRK) is to_______ GPCR so that it can bind with_______leading to inactivation of the protein.
Phosphorylate; arrestin
Receptors can be regulated by end-cytosol by either_______or disposed of by
Engulfed into the cell to be reused; lysosomes
Odarent receptors fall under which class of signalling proteins
GPCRS
Which G protein mediates inhibition of adenylate cyclase
Gi
Beta-adrenergic receptors stimulate which G-protein
Gs
Which G protein mediates calcium signalling
Gq
Transcriptions are Intracellular receptors. T/F
True
Ca similarly to cAMP is a
Second messenger
Calmodulin binds to_____Ca ions causing a conformational change
4
Phospholipases C-beta is activated by
Gq-GTP
Phospholipase c cleaves________(which is a second messenger) from PIP2, that activates a calcium channel as a result
IP3
___________ from the PIP2 and IP3 cleavage, along with calcium ions activate protein kinase C
DiAcylGlycerol
Muscle contraction can occur when calmodulin binds with________ which phosphorylates the myosin light chain
MLC kinase
Calcium release can induce further calcium release. T/F
True
Increased calcium activates__________which produces NO to bind_________, causing the synthesis of cGMP as a result
NO synthase; Guanylate cyclase
NO synthase uses which amino acid acid along with calcium to produce NO
Arginine
cGMP causes _________of smooth muscle cells
Relaxation
Guanylyl cyclase uses________and converts it to cGMP
GTP
cGMP can activate________causing vasodilation
Protein kinase G
Guanylate cyclase is activated by
NO
cGMP is converted back into GMP through which enzyme
Phosphodiesterase
Viagara works by inhibiting________preventing the conversion cGMP to GMP, keeping cGMP levels elevated and causing increased relaxation
Phosphodiesterase 5
ANF receptor also has Guanylate cyclase activity and converts GTP to cGMP. T/F
True
The hormones bradykinin and histamine will increase_________levels in endothelial cells which activatates NO synthase to produce cGMP in adjacent smooth muscle cells
Calcium
An increase in cAMP in smooth muscle cells will cause________of smooth muscle cells
Relaxation
An increase in_________levels will in smooth muscle cells cause contraction
Ca
Receptor tyrosine kinases (RTK’S) are activated by
Phosporylation
Ras is activated by_______which promotes the exchange of GDP-ras to GTP-ras.
Sos (Ras-Gef)
After RTK is activated through auto-phosphorylatio, adapter proteins with an ______Domain bind the phosphotyrosines
SH2
MAP kinase kinase kinase (raf) is activated by
An active ras protein
GEF converts_________to _________to activate a protein
GDP; GTP
GAP converts______to ______ to inactivate a protein
GTP;GDP
In apoptosis inhibitoon, PI3 kinase -phosphorylates_______ to create PIP3 which then recruits ______ and ______to the plasma membrane.
PIP2; AKT;PDK1
In apoptosis inhibition, AKT is phosphorylated by______and _______
mTOR; PDK1
In apoptosis inhibition AKT phosphorylates_________which then dissociates from apoptosis inhibitory protein and activates it.
Bad