Biosignaling Q5 Flashcards
Explain how the following signaling systems work: Autocrine, Paracrine, Synaptic, Endocrine.
Autocrine works on itself. Paracrine is usually working within an organ system. Synaptic is within synapses. Endocrine is largest domain and is released into vasculature and travels to effector organ.
What are the four components of signal transduction?
1- signal, 2- receptor, 3- transduction pathways, 4- targets.
What are the soluble signals and give an example of each.
Proteins and amino acids like epidermal growth factor. Lipids and fatty acids like ceramide and testosterone. Carbohydrates like glucose.
What is a linked signal and give an example.
Usually integrated into plasma membrane like integrin.
What are the physical signals and give example of each.
Mechanical, mechanoreceptors. Light, opsin. Temperature, TRP channels.
How does G protein- coupled receptor work?
External ligand binding to receptor activates G protein which regulates enzyme responsible for second messenger.
How does receptor tyrosine kinase work?
Ligand binding activates tyrosine kinase by autophosphorylation activating transcription factor
How does receptor guanylyl cyclase function?
Ligand binding to extracellular domain stimulates formation of second messenger cyclic GMP.
How does gated ion channel work?
Opens in response to concentration of ligand or membrane potential.
How does adhesion receptor work?
(Note integrin) binds molecules in ECM changes conformation altering interaction with cytoskeleton.
What is the dissociation constant (Kd)?
Concentration of ligand at which 50% of receptors are bound by ligand.
What are the major role for plasma membrane in signaling?
1- receptor location, 2- Ligand exposure for receptor, 3-signaling complex information, 4- endocytosis.
What is one of the benefits when using endosomes for signal transduction?
Allows for signal to stay active by increasing concentration and therefore increasing binding.
What are the two types of lipid rafts?
Caveolar and planar.
How can lipid rafts encourage promotion or inhibition of signals?
Promotion by organizing receptors and effectors in lipid rafts and inhibition by separating them.
What structure is responsible for placing receptors back onto membranes?
Recycling endosome.
What structure is responsible for sorting and sending things to the various vesicles?
Golgi.
What is responsible for sending things to a lysosome?
Late endosome.
How are things transported to the nucleus?
Through gated transport.
What protein is responsible for directing traffic along the vesicular pathways?
Rab GTPase protein.
What are some of the postranslational modifications and what are they useful for?
Phosphorylation, ubiquitination, glycosylation, oxidation, methylation, acetylation, SUMOylation. Used for allosteric regulation of enzymes.
What are the 4 common signaling cascades?
1- mitogen-activated protein kinase (MAPK this is the most common) 2- Janus kinase- signal transducer and activator of transcription (JAK-STAT) 3- Phosphatidylinositol 3-Kinase (Pi3K) 4- Phospholipase C (PLC)
What is the basic outline of MAPK signaling?
RAS activates MAP kinase kinase kinase, activating MAP kinase kinase, activating MAP kinase which acts on various proteins and regulators. Each activation step takes ATP.
What is the basic outline of JAK-STAT signaling?
JAK phosphorylates STAT at the membrane which then moves into the membrane activating transcription.
What is the basic outline for PI3K signaling?
PI3 kinase phosphorylates PIP2 to PIP3 which then is able to phosphorylate AKT which is able to act on a number of other things like protein synthesis and cell death.
What is the basic outline for phospholipase C signaling?
G proteins have three units which G alpha then activates phospholipase C.
What is the idea of cross talk in signaling?
The idea that pathways influence each other.
What are the most common targets for cell signaling?
Nucleus, actin/tubulin/filaments, enzymes, receptors, transporters, ion channels.
What types of signaling does epinephrine signaling utilize?
G-protein and PLC signaling.
What types of signaling does insulin signaling utilize?
RTK, MAPK, PI3K.
What are the responses of epinephrine binding compared to binding with epinephrine and norepinephrine?
With epinephrine you will get smooth muscle relaxation and vasodilation where with the two binding you will get smooth muscle contraction and vasoconstriction. The first uses B-adrenergic receptor and the second uses A1-adrenergic receptor.
What is the basic signaling pathway for MAPK in insulin?
insulin binds to receptor causing tails to be autophosphorylated. IRS 1 comes in and is phosphorylated and then recruits RAS leading to activation of MAPK.
How is the PI3K signaling done in insulin?
IRS-1 activates PI3K with phosphorylation activating the GS proteins synthesizing glycogen.
