Cell Communication (Chapter 9) Flashcards
Ligand
The signaling molecule
Receptor Protein
The molecule to which the receptor binds.
- May be on the plasma membrane or within the cell.
Receptor proteins have a _____ shape that fits a specific _____.
three-dimensional
signal molecule
When a signal molecule and receptor protein bind, a change in the _____ is induced and a _____ in the cell is generated.
receptor protein
response
A(n) _____ arises from a ligand binding to a receptor.
conformational change
The _____ can directly or indirectly interact with a whole host of other _____ within the cell.
receptor-ligand complex
signaling molecules
Cell signals can be induced through _____, _____, _____ (_____), and _____ (_____).
Direct contact Paracrine signaling Endocrine signaling -(hormones) Synaptic signaling -(neurotransmitters)
Cell Communication Through Direct Contact
Molecules on the surface of one cell are recognized by receptors on the adjacent cell.
Cell Communication Through Paracrine Signaling
A signal released from a cell has an effect on neighboring cells.
Cell Communication Through Endocrine Signaling
Hormones released from a cell affect other cells throughout the body.
Cell Communication Through Synaptic Signaling
Nerve cells release the signal (neurotransmitter) which binds to receptors on nearby cells.
Signal Transduction
Occurs when a ligand binds to a receptor protein, creating a response.
During signal transduction, different _____ can respond differently to the same signal.
cell types
A cell’s response to a signal often involves _____ or _____ proteins.
activating
inactivating
_____ is a common way to change the activity of a protein.
Phosphorylation
Protein Kinase
An enzyme that adds a phosphate to a protein.
Phostatase
An enzyme that removes a phosphate from a protein.
Two different classes of protein kinases:
Serine/Throenine
Tyrosine
Receptors can be defined by their _____.
location
Intracellular Receptor
Located within the cell.
Cell Surface Receptor
Membrane Receptor
Located on the plasma membrane to bind a ligand outside the cell.
Three subclasses of membrane receptors:
Channel linked receptors
Enzymatic receptors
G protein-coupled receptor (GPCR)
Channel Linked Receptors (Membrane Subclass Receptor)
Ion channel that opens in response to a ligand.
Enzymatic Receptors (Membrane Subclass Receptor)
Receptor is an enzyme that is activated by the ligand.
G Protein-Coupled Receptor (GPCR) (Membrane Subclass Receptor)
A G-protein (bound to GTP) assists in transmitting the signal.
G-protein activates an effector protein (usually an enzyme).
Ras G protein is _____, binds to _____ in its active form and _____ in its inactive form.
monomeric
GTP
GDP
Trimeric G protein has three subunits: _____, _____, and _____. It binds to _____ in its active form and _____ in its inactive form.
alpha beta gamma GTP GDP
Effector Protein
The enzyme (usually) activated by G-protein in GPCRs.
Once activated, a effector protein produces a _____ which generates the _____ to the original signal.
second messenger
cellular response
One common effector protein is _____ which produces _____ as a second messenger.
adenylyl cyclase
cAMP
cAMP binds to _____ and activates it.
Protein Kinase A
Another common effector protein is _____.
Phospholipase C
_____ is acted on by effector protein Phospholipase C.
PIP(sub2)
Phospholipase C produces _____ plus _____.
IP(sub3)
-Inositol Tris Posphate
DAG
-Diacyl Glycerol
PIP(sub2) and IP(sub3) act as _____.
second messengers
cAMP Signaling Pathway
- Ligand binds to GPCR
- GDP phosphorylated to GTP by protein kinase
- GTP binds to Adenylyl Cyclase, producing cAMP.
- cAMP binds to and activates Protein Kinase A (PKA), producing a response protein.
Ca2+ serves widely as a _____.
second messenger
_____ levels of Ca2+ are normally low.
Intracellular
_____ levels of Ca2_ are normally high.
Extracellular
The _____ has receptor proteins that act as ion channels to release Ca2+. These receptor proteins bind most commonly to IP(sub3).
endoplasmic reticulum
Most signaling molecules exist in such _____ concentration, diffusion across the cytoplasm requires _____.
low
amplification
A single cell surface receptor can stimulate a _____ to amplify the signal.
cascade of protein kinases
Different receptors can produce _____ second messengers.
the same
The hormones _____ and _____ can both stimulate liver cells to mobilize glucose.
glucagon
epinephrine
Single signaling molecules can have _____ effects in different cells.
different
Multiple forms of the same receptor are called _____ or _____.
subtypes
isoforms
The receptor for epinephrine has _____ isoforms, each encoded by different _____.
nine
genes
Different isoforms activate different _____, leading to different _____.
G proteins
signal transduction pathways
A steroid hormone receptor has three functional domains: _____, _____, and _____.
hormone-binding domain
DNA binding domain
domain that interacts with co-activators to affect gene expression
Intracellular receptors can act as _____ and _____.
gene regulators
enzymes
The target cell’s response to a _____ can vary enormously.
lipid-soluble cell signal
Estrogen has different effects in _____ tissue than _____ tissue.
uterine
mammary
Receptor tyrosine kinases are _____ receptors.
membrane
Receptor tyrosine kinases, when bound by a ligand, are activated by _____ and then _____.
dimerization
autophosphorylation
Receptor tyrosine kinases, when activated, add a _____ to a _____.
phosphate
response protein
Mitogen-activated protein (MAP) kinases stimulate _____.
cell division.
Mitogen-activated protein (MAP) kinases are activated by a _____.
kinase cascade
phosphorylate each other in succession
Mitogen-activated protein (MAP) kinases _____ the signal.
amplify
Ras proteins are small _____.
GTP-binding proteins
Ras proteins link the _____ and the _____.
RTK
MAP kinase cascade
Ras proteins are _____ in many human tumors.
mutated.
Ras proteins are indicated to play a centrol role in linking _____ to their cellular response.
growth factor receptors
Ras can _____.
regulate itself.
Scaffold proteins are thought to organize the components of a _____ into a single _____.
kinase cascade
protein complex
Scaffold proteins bind to each individual _____ such that they are spatially organized for optimal function.
kinase
Scaffold proteins benefit in _____.
efficiency
Scaffold proteins are disadvantaged in that they reduce the _____.
amplification effect
Cells contain an array of _____ on the cell surface.
marker proteins
Glycolipids
Tissue-specific cell surface markers.
Major histocompatibility complex (MHC) proteins
Identify self versus non-self cells.
