Cell Signaling Flashcards
Signaling molecule
Ligand
A molecule that ligands bind to
Receptor Protein
What process does the binding of a ligand to a receptor protein initiate?
Signal Transduction
Signaling cells that can also bind to the ligand that is released, such that signal and target cell can be the same/similar to each other; cell targets itself
Autocrine Signaling
Intracellular mediators that allow small signaling molecules to move between cells; cell targets other cell connected by gap junctions
Direct Signaling Across Gap Junctions
Move by diffusion through extracellular matrix (ex: synaptic signals and neurotransmitters; cell targets nearby cell
Paracrine Signaling
Signals from distant cells that typically produce a slower response with long-lasting effect (ex: hormones); cell targets distant cell through bloodstream
Endocrine Signaling
Why is autocrine signaling important?
Important for cell death
When does autocrine signaling occur?
Early development
What does autocrine signaling regulate?
Pain sensation
What is direct contact signaling important in?
Early development
What type of response does paracrine signaling initiate?
Quick and short-lived with local effects
In what does paracrine signaling occur?
Animals
What organisms use endocrine signaling extensively?
Animals and plants
What type of receptor is located within a cell and bind with hydrophobic ligands that can easily cross the plasma membrane?
Intracellular Receptor
What type of receptor is located on the plasma membrane to bind hydrophilic ligands outside the cell?
Cell Surface/Membrane Receptor
Enzyme that adds a phosphate to a protein
Protein Kinase
Enzyme that removes a phosphate from a protein
Phosphatase
Channel-linked receptors that open to let a specific ion pass in response to a ligand
Chemically Gated Ion Channels/Ion Channel-Linked
Receptor is an enzyme that is activated by the ligand; almost all are protein kinases
Enzymatic Receptors
G-protein (bound to GTP) assists in transmitting the signal from receptor to enzyme
G-Protein Coupled Receptors
What generates second messengers?
Membrane Receptors
Small molecules that propagate a signal after it has been initiated by the binding of the signaling molecule to the receptor
Second Messenger
Protein that functions to link transcriptional activators to the transcription complex
Coactivators
Influence cell cycle, cell migration, cell metabolism, and cell proliferation and is a membrane receptor; alteration to function can lead to cancer
Receptor Tyrosine Kinase (RTK)
What are RTKs composed of?
Single transmembrane protein, extracellular ligand-binding domain, intracellular kinase domain (catalytic site of receptor acts as a protein kinase)
What happens when a ligand binds to an RTK?
Dimerization and autophosphorylation occur and cellular response follows
What is a kinase cascade?
Series of protein kinases that phosphorylate each other in succession and amplified the signal because a few signal molecules can elicit a large cell response
Thought to organize the components of a kinase cascade into a single protein complex and binds to individual kinase; must rely on substrates being near
Scaffold Proteins
Small GTP binding protein that is the link between the RTK and MAP kinase cascade; mutated in many human tumors
Ras Proteins
Protein bound to GTP
G-Protein
Receptors bound to G proteins where a G protein is a switch turned on by the receptor and activates an effector protein
GPCR (G-Protein Coupled Receptor)
When are G-proteins active?
When bound to GTP
What composes most effector proteins?
Enzymes
What does adenylyl cyclase produce?
cAMP
What does cAMP do?
Binds and activates PKA which phosphorylates specific proteins
What are examples of second messengers?
Calcium, inositol phosphates, phospholipase C
