Chapter 9 - Cell Communication Flashcards
What does effective signaling require?
Ligand and Receptor Protein
Signaling molecule (amino acid, peptide, large protein, individual nucleotides, steroids, lipids, dissolved gases such as Nitrous Oxide NO)?
Ligand
Molecule to which signal binds?
Receptor Protein
Where are receptor proteins located?
On plasma membrane or within a cell
Complex made of ligand and receptor protein
Complex ligand-receptor
what is signal transduction
signal that results in a cellular response
How does signal response work
Cell responds to only one signal and ignores the rest depending on kind and number of receptors
What is the general process of signal transduction
Ligand binds to receptor with complementary shape, induced change of receptor shape, initiation of signal transduction pathway, cellular response
What are the basic mechanisms of Cellular Communication
1- Direct Contact
2- Paracrine Signaling
3- Endocrine Signaling
4- Synaptic Signaling
What is direct contact
cells are close to each other & molecules on surface of cells are recognized by receptors of adjacent cell.
Examples of direct contact
Embryonic development
Gap Junction
What is Paracrine Signaling
signal molecules diffuse through extra-cellular fluid to nearby cells & only affects nearby cells
Characteristics of signals in Paracrine Signaling
Short-lived & Local Effect
Examples of Paracrine Signaling
early development, immune cells, and growth factors
What is endocrine signaling
signal molecules enter the circulatory system and travel through the body
Where do secretions of endocrines go
Travel to distant cells
Characteristics of signals in Endocrine Signaling
long-lived & distant effect
Examples of Endocrine Signaling
Hormones
What are the signal molecules in synaptic signaling
Neurotransmitters released by nerve cells
What is synaptic signaling
Neurotransmitters travel from tip of nerve cells to nearby target cells through a synaptic gap
What is a chemical synapse
Neuron & Target cell
Characteristics of signal in synaptic signaling
Short-lived & brief effect
examples of synaptic signaling
acetylcholine, glutamate, and GABA
what is autocrine signaling
cells secrete signals that bind to specific receptors on their own plasma membrane
they respond express and respond to secreted signals
examples of autocrine signaling
signaling in immune system
what are signal transduction pathways
complex and discrete pathways
what is signal transduction
events that occur on receipt of a signal
what is the path for signal transduction
Ligand binds to receptor protein, forms complex, response
what is protein phosphorylation
control of protein function
what does protein kinases do
add phosphate from ATP to a protein
what is dephosphorylation
removal of a phosphate group from a protein
relation of phosphorylation and dephosphorylation to a protein
protein is activated by phosphorylation.
deactivated by phosphorylation
reverse works
how are receptors defined
by location and specific ligand binding
Characteristics of intracellular receptors
In cytoplasm and bind to hydrophobic ligands inside the cell
Characteristics of membrane receptors
transmembrane protein in plasma membrane, cytoplasmic or extracellular domain, bind to hydrophobic ligands outside the cell
Characteristics of Cell surface receptors
transmembrane protein in plasma membrane, cytoplasmic or extracellular domain, bind to hydrophobic ligands outside the cell
Types of Cell surface/membrane receptors
Channel-linked, enzymatic, and G-protein coupled receptors
characteristics of channel-linked receptors
Chemically/ligand gated ion channel, no energy needed, moves down concentration gradient
characteristics of enzymatic receptors
integral mb proteins, act or linked to enzyme, catalytic rxn on cytoplasmic portion, protein kinases
characteristics of G-protein coupled receptors
integral mb proteins, linked to G-protein
what causes G-protein conformation change
ligand binding
characteristics of steroid hormones
small, non-polar, bind to steroid hormone receptor, pass through plasma mb
function of steroid hormone
regulation of gene expression, production of proteins
functional domains of steroid receptors
hormone-binding, DNA-binding, interacts with coactivators to affect gene expression
inactive state of steroid receptor
inhibitor protein occupies DNA binding sight
hormone activation of steroid receptor
signals bind, change of receptor, inhibitor release, exposed DNA binding sight, receptor activation
gene expression activation of steroid receptor
receptor binds to DNA nucleotide seq in the nucleus, cell response is change I gene expression
how do coactivators work
intracellular responses act in concert with coactivators
difference in cell responses to the same signal is due to
number + nature of coactivators
how does the estrogen hormone affect the mammary tissue
coactivator is lacking, hormone interacts with another protein, gene expression decreases
how does the estrogen hormone affect the uterine tissue
presence of coactivator, complex estrogen-receptor binds to coactivator, gene expression increases (prepare uterus for pregnancy)
what is the receptor for NO gas
Guanylyl cyclase complex
how does Guanylyl cyclase complex work
NO binds to it, activating it, then catalyzes the synthesis of cGMP
what is the receptor for viagra
Sildenafil - cGMP phosphodiesterase complex
what is a protein kinase
enzymatic receptors that alter protein function by phosphorylation
what is an RTK
Receptor Tyrosine Kinases
Function of RTK
recognize hydrophilic ligands
Signaling via RTK influences what processes
cell cycle
cell migration
cell metabolism
cell proliferation
stimulate cell division
Mutations in RTK or Alterations of RTK signaling pathways can cause
cancer
Continuous signaling from RTK causes
Continuous cell proliferation
what is a plant receptor kinases
serine-threonine kinases
structure of RTK
single transmembrane domain, extracellular ligand-binding domain, intracellular kinase domain (catalytic site)
what does the catalytic site do
acts as a protein kinase that phosphorylates tyrosine
what occurs upon ligand binding
Dimerization & autophosphorylation
what is Dimerization
2 receptor-ligand complexes associate together
what is autophosphorylation
2 receptor-ligand complexes phosphorylate eachother
what does activation of the tyrosine kinase domain do
phosphorylation of intracellular targets (response proteins)
what does an activated receptor do
add phosphate to tyrosine on response protein
what does cell response depend on
type of response proteins inside the cell
what is a phosphotyrosine?
phosphorylated region outside the catalytic site
how are intracellular events initiated?
proteins bind to phosphotyrosine
