Intracellular signaling - Bayer Flashcards
What are the principle types of detectors of extracellular signaling?
Ligand or voltage gated ion channels
GPCRs (G-coupled protein receptors)
Enzyme linked receptors (including receptor tyrosine-kinases)
(Nuclear receptors) - [activated by cell penetrating signaling molecules]
What are the 4 types of extracellular signaling?
autocrine -> cell produces self targeted ligand
paracrine -> when the target is a nearby cell
endocrine -> when the ligand is secreted into the blood stream
neurotransmitter -> when the target is a nerve cell
What are second messengers?
small molecules
generated or released in response to 1st messenger (ligand that stimulates receptor)
Can regulate the activity of intracellular signaling molecules
What is an agonist?
substance that binds a receptor of a cell and triggers a response by that cell
What is an antagonist?
substance that causes the action of an agonist to be blocked
Name at least 3 second messengers
Ca 2+ (through ion channels from extracellular space or intracelluar stores)
cAMP (generated by AC- adenylate cyclase)
IP3 - inositol triphosphate (released into cytosol - generated by PCL - phospholipase C)
DAG - diacylglycerol (stays in membrane - generated by PLC)
NO - nitric oxide (generaed by NOS - nitric oxide synthase - cell permiable
What are the types of protein modification?
protein phosphorylation/ dephosphorylation (mediated by kinases/ phosphates)
Acetylation (histones)
Glycosylation (trafficking through ER, golgi, etc)
Ubiquination
Proteolytic clevage (of inactive precursors)
How does protein-protein binding/ protein targeting regulate cell signaling?
by promoting access to downstream substrates
preventing access to other substrates
How can an extracellular signaling molecule terminante a signal?
Taken up into cells
reused
broken down extracellularly
diffuse to lower concentration
What are 3 ways beyond an extracellular signaling molecule that signals can be terminated?
another signal (phosphorylation reverses dephosphorylation)
Enzyme dedicated to turning off signals (phosphodiesterase - PDEs hydrolyze cAMP and cGMP)
Built in terminators ( g-proteins, Ras-like proteins)
negative feedback loop
What is amplification
When one upstream signaling molecule can activate more than one downstream signaling molecule
ex. positive feedback loop
What is a signaling cascade?
Description of pathway where amplification occurs at multiple steps
What is cross talk?
A result of complex signaling network
- simultaneous activity/ inactivity of several receptor types may be required to cause signaling outcome (coincidence detection)
What is a signaling node?
Location in the network that receives multiple inputs and multiple outputs
What is one of the most extensive signaling nodes?
Ca+
i.e. links 6 specific signals with 6 specific outputs
