Principles of Cell Signaling Flashcards
What are the signal types
Contact dependent
Paracrine
Synaptic
Endocrine
What are the cell signal types organized by distance signal travels
Local (autocrine, contact-dependent, paracrine, synaptic)
Long distance (endocrine)
What is the most common form of signaling
Paracrine
How does paracrine signaling work
Cells respond to signaling molecules locally released by signaling cell
How are responses kept local during paracrine signaling
Ligands are quickly degraded by enzymes or removed by neighboring cells
How does autocrine signaling work
Signaling and target cell are the same, so cells respond to signaling molecules that they produce themselves
What are some examples of cells that do autocrine signaling
Immune cells
Cancer cells
How does synaptic signaling work
Neurotransmitters are the signals
Paracrine signaling - speed and concentration of signals
Fast
Relatively concentrated
How does endocrine signaling work
Endocrine cell secretes a hormone
Hormone travels in blood to target
Endocrine signaling - speed and concentration of signals
Slow - relies on blood flow and diffusion
Dilute - low concentrations of hormones
How does contact-dependent signaling work
Cell-cell signaling that requires close contact
Can be membrane-bound signaling molecules or be shared through gap junctions
What are some types of ligands
Proteins, peptides, amino acids, small molecules. lipids, ions
What are ligands
Chemical signals for cell communication
What are the classes of signaling receptors
G-protein coupled receptors
Enzyme-linked receptors
Ligand-gated ion channels
Nuclear receptors
General rundown of GPCRs
Transmembrane receptor at cell surface
Binds extracellular ligands
Binding activates G protein
Types of enzyme-linked receptors
1 - intrinsic enzymatic activity (enzyme-coupled)
2 - enzyme-associated receptor
General rundown of enzyme-coupled receptors
Extracellular ligand binds and induces dimerization
Activates catalytic activity on cytoplasmic side
General rundown of enzyme-associated receptors
Extracellular ligand binds
Enzyme recruited and activated on the cytoplasmic side
General rundown of intracellular receptors
Intracellular - cytoplasm or nucleus
Receptors bind to DNA and alter transcription
General rundown of ligand-gated ion channels
Cell-surface transmembrane receptors
Ions are signaling molecules
What are the steps of the signaling cascade
Reception
Transduction
Response
What happens during reception
Ligand binds to receptor protein
Receptor protein changes shape
Change in shape begins a series of events
What happens during transduction
A series of events “transduces” signal
Signal is often amplified
What organized the signaling proteins during transduction?
Scaffold proteins
What is the result of transduction (eg. the next step)
response - activation of effector proteins (trans. regulation, enzyme, etc)
Behavior of the cell is altered
What is convergent signaling?
Signals from unrelated receptors converge to activate the same effector
What is divergent signaling
One signal diverges to act on different receptors
What is cross-talk
When signals move between pathways
Can all cells receive a certain signal?
No, cells must have the receptor appropriate to the signal
Do all ligands produce the same results?
No. Ex. - acetylcholine has different results for skeletal vs heart muscle
