Cell Signaling by Chemical Messengers Flashcards
Cell signaling vs. signal transduction
Signaling - between cells
Signal Transduction - extracellular signal converted to intracellular response
Cell signaling steps
Chemical messenger secreted by cell bc of stimulus
Messenger diffuses and transported to target cell
Specific receptor binds messenger
Binding elicits response
Termination
Specifity of receptor dictated by
Type of receptor and location
Most receptors bind
A single messenger type
Endocrine signaling
Cell sending out signal is pretty far away…usually transported through blood
Paracrine signlaign
Signaling cell is close
Autocrine signaling
Cell signals to itself
Nervous system messenging molecules and type
Small molecule neurotransmitters and neuropeptides
Paracrine
Endocrine system molecules and type
Endocrine
Endocrine hormones
Glucagon is ______ system and does what
Response to low glucose levels
Glycogenolysis
Endocrine
Immune system molecules and type
Cytokines
Auto, para, and endo
Eicosanoids molecules and types
Derived from arachidonic acid
Control response to injury
Para and auto
Growth factors molecules and type
Proliferation, differentiation, and apoptosis
Paracrine
4 receptor types from fast to slow
Channel-linked receptors (ionotropic)
GPCR (metabotropic)
Kinase-linked
Nuclear receptors (linked to gene transcription)
What can nuclear receptors bind?
Things that can get through membrane into the nucleus
Channel-linked receptors also known as
Gated ion channels
Agonist
Messenger that opens an ion channel
Example of Gated ion channel
Nicotinic acetylcholine receptor
Nicotinic acetylcholine receptor…what does it do, where is it found
Neuromuscular junctions - muscle contractions
Sense Ach and lets Na in and K out of muscle fiber
Nicotinic acetylcholine mechanism
AP in motor neruon
V gated ion channel lets Ca into cell
Vesicle of Ach fuses at post synaptic membrane
Ach diffuses and binds nicotinic acytylcholine receptor
Propogates signal through muscle fiber
How is acetylcholine receptor mechanism turned off?
Acetylcholinesterase degrades Ach
Myasthenia Gravis is what kind of disorder?
Acquired autoimmune
MG pathology
Produce antibodies to nicotinic Ach receptor…antibodies bind and cross-link receptor…complex andocytosed and degraded by lysosome…patient has fewer neuromuscular junctions and therefore lots of muscle fatigue
MG symptoms
Difficulty walking
Difficulty extending arms
Drooping eyelids
Tyrosine kinase receptors mechanism
Signal dimer binds
Kinase activity stimulated in the cytosol
Tyrosines phosphorylated
Intracellular proetins bind to phospho-tyrosine binding site
Tyrosine kinase receptors form _____ dimers
Homo
Tyrosine kinase external/internal domains
External - receptor
Internal - tyrosine kinase
Ras mutations
Mutations that turn Ras on will cause cancer
Ras causes
Proliferation, survival, and growth
Ras pathway
EGF binds EGFR (receptor tyrosine kinase)…recruits GRB2…Recruits SOS…Recruits Ras…Ras phosphorylates Raf…phosphorylates…MEK…Phosphorylates Erk…acts on DNA
Serine/threonine kinase messengers
TGF beta and Bone morphogenic factors
Serine/threonine kinase signal
Smad proteins
Serine/threonine kinase forms _____dimer
Hetero
Nuclear receptors are
Intracellular proteins with extracellular messengers
Messengers of nuclear receptors are typicall _____ and example
Hydrophobic
Steroids
2 types of steroid hormones
Cytoplasm (glucocorticoid)
Nucleus (more common)
Glucocorticoids include
Cortisol, corticosterone, and aldosterone
Cortisol regulates
Cardiovascular, metabolic, and immuno functions
Glucocorticoid pathway
Glucocorticoid binds receptor that has chaperone proteins attached…chaperones leave…GR dimerizes and binds to DNA causing changes
Cortisol released from ___ in response to ____
adrenal cortex
Chronic stress
Cortisol acts n various tissues to do what in acute stress?
Change enzyme levels and redistribute nutrients
Cortisol and liver
Can upregulate liver proteins in gluconeogenesis to provide rapid response to hypoglycemia
PPAR receptor messenger and response
Fatty acids and derivatives
Regulate transcription of genes
PPAR pathway
Bind PPAR…PPAR dimerizes with RXR…binds to DNA to function
Gap junction other names
Nexus
Macula communicans
Gap junctions connect
Cytoplasm of 2 cells
Gap junctions allow passage of
Molecules and electrical impulses
Gap junctions not found in
Skeletal muscle or mobile cell types
Gap junction consists of two
Connexons (hemichannels) one on each cell
Eahc connexon is
Homo/hetero hexamer of connexin proteins
Gap junction size exclusion
500 Da
Gap junctions are especailly important in
Heart
