exam 4 Flashcards
Which of the following is a short-range signaling mechanism that enables cells to signal to other cells via secreted local mediators?
endocrine
Which of the following binding domains enables proteins to bind to phosphoinositides?
PH
The secondary messenger, cAMP activates which enzyme?
PKA
Protein that binds to a GTP- binding protein and activates it by stimulating release of tightly bound GDP, thereby allowing it to bind GTP
Guanine nucleotide exchange factor (GEF)
General term for a protein that binds a specific extracdllular molecule (ligand) and initiates a response in the cell
receptor
Alteration of sensitivity following repeated stimulation, reducing a cells response to that level of stimulus
adaptation or desensitization
Compact protein module that binds to a particular structural motif in another protein (or lipid) molecule with which the signaling protein interacts
interaction domain
Short-range cell-cell communication via secreted local mediators that act on adjacent cells
paracrine signaling
A signal relay chain involving multiple protein kinases, each of which is activated by phosphorylation and then phosphorylates the next protein kinase in the sequence
kinase cascade
Small molecule that is formed in the cytosol, or released into it, in response to an extracellular signal and that helps to relay the signal to the interior of the cell
second messenger
Specialized animal cell that secretes a hormone into the blood
endocrine cell
Molecule from outside the cell that communicates the behavior or actions of other cells in the environment and elicits an appropriate response
extracellular signal molecule
Enzyme that transfers the terminal phosphate group of ATP to a specific amino acid of a target protein
protein kinase
Small signal molecule secreted by the presynaptic nerve cell at a chemical synapse to relay the signal to the postsynaptic cell
neurotransmitter
Protein that binds to a GTP-binding protein and inactivates it by stimulating its GTPase activity so that its bound GTP is hydrolyzed to GDP
GTP-ase activating protein
Protein that organizes groups of interacting intracellular signaling proteins into signaling complexes
scaffold protein
Cell-cell communication in which the signal molecule remains bound to the signaling cell and only influences cells that physically touch it
contact-dependent signaling
G protein that activates adenylyl cyclase and thereby increases cyclic AMP concentration
stimulatory G protein
Protein composed of three subunits, one of which is activated by the binding of GTP
trimeric GTP-binding protein
Ubiquitous calcium-binding protein whose interactions with other proteins are governed by changes in intracellular Ca2+ concentration
Calmodulin
Enzyme that hydrolyzes cyclic AMP to adenosine 5’-monophosphate (5’-AMP)
cyclic AMP phosphodiesterase
Cell-surface receptor that associates with an intracellular G protein upon activation by an extracellular ligand
G-protein-coupled receptor
Enzyme that participates in desensitization of GPCRs by phosphorylating them after they have been activated by ligand binding
GPCR kinase
Ca2+ release channel in the ER membrane that is activated by Ca2+ binding in the absence of IP3
ryanodine receptor
Enzyme bound to the cytoplasmic surface of the plasma membrane that converts membrane PI(4,5)P2 to diacylglycerol and IP3
phospholipase C-B (PLCB)
Protein that is an a-subunit-specific GTPase-activating protein (GAP)
regulator of G protein signaling (RGS)
Second messenger that is released from a phospholipid in the plasma membrane and diffuses to the ER, where it opens Ca2+ release channels
inositol 1,4,5-triphosphate (IP3)
Enzyme that phosphorylates target proteins in response to a rise in intracellular cyclic AMP
cyclic AMP-dependent protein kinase (PKA)
A Ca2+ dependent protein kinase that is activated by diacylglycerol
protein kinase C (PKC)
Light sensitive GPCR in rod photoreceptor cells of the retina
rhodopsin
Protein kinase whose activity is regulated by the binding of Ca2+ activated calmodulin, and which indirectly mediates the effects of Ca2+ by phosphorylation of other proteins
Ca2+/calmodulin-dependent kinase (CaM-kinase)
Protein that binds to the cyclic AMP response elements found in the regulatory region of many genes activated by cyclic AMP
CRE-binding (CREB) protein
The largest class of cell-surface-bound extracellular signal proteins
Ephrins
Large family of structurally related, secreted, dimeric proteins that act as hormones and local mediators to control a wide range of biological function in all animals
transforming growth factor-B superfamily (TGFB)
Cell-surface receptor that when activated by ligand binding adds phosphates from ATP to tyrosine side chains in its own cytoplasmic domain
receptor tyrosine kinase (RTK)
The founding member of a superfamily of monomeric GTPases that help to relay signals from cell-surface receptors to the nucleus
Ras
A group of monomeric GTPases that regulate both the actin and microtubule cytoskeletons
Rho family
Cytoplasmic tyrosine kinase present at cell-matrix junctions in association with the cytoplasmic tails of integrins
focal adhesion kinase (FAK)
A kinase that is involved in intracellular signaling pathways activated by cell-surface receptors and that phosphorylates inositol phospholipids at the 3 position of the inositol ring
phosphoinositide 3-kinase (PI 3-kinase)
Cell-surface receptor that activates a tyrosine kinase that is noncovalently bound to the receptor
tyrosine-kinase-associated receptor
A three-component signaling module used in various signaling pathways in eukaryotic cells
MAP kinase module
One of several intracellular signaling pathways that leads from cell-surface receptors to the nucleus, it is distinguished by providing one of the more direct routes
JAK-STAT signaling pathway
Protein domain found in intracellular signaling proteins by which they bind to inositol phospholipids phosphorylated by PI 3-kinase
Pleckstrin homology (PH) domain
A protein domain that is homologous to a region in Src, is present in many proteins, and binds to a short amino acid sequence containing a phosphotyrosine
SH2 domain
A crucial signaling protein in the PI-3-kinase-Akt signaling pathway, so named because it is the target of rapamycin
TOR or mTOR
Receptor protein involved in what may be the most widely used signaling pathway in animal development; its ligands are cell-surface proteins such as Delta
Notch
A family of secreted signal molecules that act as local mediators and morphogens during development; they were initially discovered as the products of the Wingless gene in flies and the Int1 gene in mice
Wnt proteins
A signaling pathway activated by Wnt binding to both the Frizzled receptor and the LRP co-receptor
Wnt/B-catenin pathway
A group of secreted signal molecules that act as local mediators and morphogens during development and whose effects are mediated through the cell-surface receptor Patched and its binding partner Smoothened
Hedgehog proteins
A target of Hedgehog signaling, this gene regulatory molecule is a full length gene activator in the presence of Hedgehog and a partially proteolyzed gene repressor in its absence
Cubitus interruptus (Ci)
Latent gene regulatory proteins that are present in most cells in both animals and plants and are central to many stress, inflammatory, and innate immune responses
NFKB proteins
Hydrophobic signaling molecule with a characteristic four-ringed structure derived from cholesterol
steroid hormone
A linear chain of protein subunits joined end to end, which associates laterally with other such chains to form cytoskeletal components
protofilament
System of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell its shape and the capacity for directed movement
cytoskeleton
The process by which a polymeric protein filament is maintained at constant length by addition of protein subunits at one end and loss of subunits at the other
treadmilling
Specialized layer of cytoplasm on the inner face of the plasma membrane, rich in actin filaments
cell cortex
Protein assembly that nucleates actin filament growth from the minus end, allowing rapid growth at the plus end and forming a treelike web of filaments
Arp2/3 complex
The motor protein in muscle that generates the force for muscle contraction
myosin
Long, highly organized bundle of actin, myosin, and other proteins in the cytoplasm of muscle cells that contracts by a sliding-filament mechanism
myofibril
The property of sudden conversion feom growth to shrinkage, and vice versa, in a protein filament such as a microtubule or an actin filament
dynamic instability
Centrally located organelle of animal cells that is the primary microtubule-organizing center and acts as the spindle pole during mitosis
centrosome
Protein assembly containing a special form of tubulin, along with other proteins, that is an efficient nucleator of microtubule growth
y-Tubulin ring complex (y-TuRC)
Short cylindrical array of microtubules, a pair of which are embedded in the major microtubule-organizing center of an animal cell
centriole
A member of the family of motor proteins that move along microtubules by walking toward the minus end
dynein
A motor protein that moves along microtubules by walking toward the plus end
kinesin
Bundle of mixrotubules and associated proteins that forms the core of a cilium or flagellum in a eukaryotic cell and is responsible for their movements
axoneme
Long, hairlike protrusion from the surface of a eukaryotic cell whose endulations drive the cell through a liquid medium
flagellum
A group of closely related monomeric GTPases that includes Cdc42, Rac, and Rho
Rho family protein
Flattened, two-dimensional protrusion of membrane, supported by a meshwork of actin filaments, that is extended from the leading edge of crawling epithelial cells, fibroblasts, and some neurons
lamellipodium
Essentially a one-dimensional structure that protrudes from a cell and contains a core of long, bundled actin filaments
filopodium
A distinct form of membrane protrusion that is often observed when cells are cultured on a pliable extracellular matrix substrate
blebbing
The long period of the cell cycle between one mitosis and the next
interphase
The orderly sequence of events by which a cell duplicates its contents and divides into two
cell cycle
The checkpoint in the cell cycle that governs the cell’s commitment to enter S phase
Start or restriction point
The phase of the eukaryotic cell cycle between the end of cytokinesis and the start of DNA synthesis
G1 phase
A member of the family of protein kinases that have to be complexed with a cyclin protein in order to act
Cyclin-dependent kinase(Cdk)
The ubiquitin ligase that promotes the destruction of a specific set of proteins, thereby promoting the separation of sister chromatids and the completion of M phase
anaphase promoting complex or cyclosome (APC/C)
The cyclin-Cdk complex responsible for stimulating entry into mitosis at the G2/M checkpoint
M-Cdk
One of a family of proteins that rise and fall in concentration in step with the eukaryotic cell cycle, thereby regulating the activity of the crucial protein kinases that control progression through the cell cycle
cyclin
The final major checkpoint in the cell cycle, where the control system stimulates sister-chromatid separation, leading to the completion of mitosis and cytokinesis
metaphase-to-anaphase transition
A timing mechanism that triggers events of the cell cycle in a set sequence, using feedback from the processes it controls ro ensure that one stage is complete before the next one begins
cell-cycle control system
General term for one of the several protein assemblies that form periodically during the cell cycle as the level of cyclin increases, and partially activate the cyclin-dependent kinase component
cyclin-Cdk complex
Complex of proteins that holds sister chromatids together along their length until they separate at mitosis
cohesin
Large protein complex that is bound throughout the cell cycle at origins of replication in eukaryotic chromosomes
origin replication complex (ORC)
Protein that binds to and inhibits ankey component of the prereplicative complex
geminin
Movement of tubulin subunits toward the spindle poles as a result of addition of new subunits at the plus ends of microtubules and their disassembly at minus ends
microtubule flux
Stage of mitosis in which the spindle poles move apart
anaphase B
Mechanism ensuring that cells do not enter anaphase until all chromosomes are correctly bi-oriented on the mitotic spindle
spindle assembly checkpoint
Centrally located organelle of animal cells that after duplication organizes each spindle pole suring mitosis
centrosome
Imaginary plane midway between the spindle poles in which chromosomes are positioned at metaphase
metaphase plate
Microtubules that overlap in the spindle midzone and interact via their plus ends, generating an antiparallel array
interpolar microtubules
Final stage of mitosis in which the two sets of separated chromosomes decondense and become enclosed by nuclear envelopes
telophase
Complex of proteins that uses the energy of ATP hydrolysis to promote the compaction and resolution of sister chromatids
condensin
Protease whose activation at the end of metaphase results in the cleavage of cohesin and the separation of sister chromatids
separase
Microtubule that radiates outward from the spindle pole and contacts the cell cortex, helping to position the spindle in the cell
astral microtubule
Cytoplasm containing many nuclei enclosed by a single plasma membrane
syncytium
Structure formed at the end of cleavage that can persist for some time as a tether between the two daughter cells
midbody
Division of the cytoplasm of a plant or animal cell into two
cytokinesis
Structure made of microtubules and actin filaments that forms in the prospective plane of division of a plant cell and guides formation of the cell plate
phragmoblast
Circular band containing actin and myosin that forms under the surface of animal cells undergoing cell division and contracts to pinch the two daughter cells apart
contractile ring
Protease that has a cysteine at its active site and cleaves its target proteins at specific aspartic acids
caspase
Wheel-like assembly composed of seven copies of the Apaf1/cytochrome c complex
apoptosome
Form of cell death that leads fo fragmentation of the DNA, shrinkage of the cytoplasm, membrane changes, and cell death, without lysis or damage to neighboring cells
apoptosis
An assembly of several proteins, including initiator caspases, on the cytosolic portion of the Fas death receptor
Death-inducing signaling complex (DISC)
Apoptotic program triggered by the binding of an extracellular signal protein
extrinsic pathway
Extracellular signal molecule that inhibits apoptosis
survival factor
Apoptotic program that depends on the release into the cytosol of proteins from the mitochondrial intermembrane space
intrinsic pathway
Cell-surface molecule that triggers apoptosis when bound by an extracellular signal protein
death receptor
When cleaved by an initiator caspase, this protease is activated and participates in the widespread cleavage events that kill the cell
executioner caspase
Ras is activated by Sos. What type of protein is Sos?
GEF
MEK is downstream of Ras and activates the MAP kinase, ERK. What type of enzyme is MEK?
MAP kinase kinase
What type of transcription factors do the JAKs regulate?
STAT
In a growing actin filament, which end typically grows fastest?
plus end
Which of these actin-binding proteins is required for the formation of Z-disks in skeletal muscle cells?
Alpha-actinin
Listeria travels around within cells by constructing actin filaments using host proteins and bacterial proteins. Which of the following proteins is a bacterial protein found on the outer surface of Listeria?
Acta
When are microtubules most stable?
when the beta subunit is binding GTP
Microtubules radiate out from the MTOC. Which ends are furthest away from the centrioles?
plus ends
What transmembrane proteins are present in focal adhesions that help cells gain traction with the extracellular matrix?
myosin
Which of the following proteins is involved in the disassembly of actin filaments behind the leading edge of a migrating cell?
cofilin
Which cyclins would you expect to be highly expressed during G1?
Cyclin D
Which of the following regulatory proteins inhibits the activity of certain cyclin:Cdk complexes?
Wee1
If cells are exposed to DNA-damaging agents they might upregulate…
p21
What is the role of separase enzymes during the cell cycle?
cleave cohesins
Which conditions can activate p53?
DNA double strand breaks caused by exposure to x- or gamma rays
DNA damage caused by UV exposure
excessive stimulation of mitogenic pathways
Which transcription factor is inhibited by active Rb proteins?
E2F
Which of the following is an anti-apoptotic member of the Bcl-2 family?
BclXl
In the extrinsic pathway of apoptosis, what role does caspase-8 play?
it is an initiator caspase
Name the different types of intercellular signaling
contact dependent
paracrine
endocrine
synaptic
Name the types of cell surface receptors
ion-channel-coupled receptors
G-protein-coupled receptors
Enzyme-coupled receptors
How are RTKs activated?
by signaling proteins that cause dimerization and trans-autophosphorylation
What are the 3 main types of cytoskeletal protein filament?
actin, microtubules, intermediate filaments
What is the location within the cell of actin?
actin is highly concentrated in the cortex just beneath the plasma membrane
What is the location within the cell of intermediate filaments?
they can be beneath the inner nuclear membrane as nuclear lamina or extend across the cytoplasm
What are microtubules attached to?
a microtubule organizing center (MTOC) called a centrosome
What is nucleation?
it is the rate limiting step in the formation of cytoskeletal polymers
What does troponin do?
controls skeletal muscle contraction by a troponin complex of T, I, and C polypeptides; tropomyosin binding, inhibitory activity, and Ca2+ binding (TIC)
Role of tropomyosin?
Prevents myosin cross bridging with actin in the absence of Ca2+
Smooth muscle contraction requires?
Ca2+ dependent calmodulin to activate MLCK or myosin light chain kinase
What is kinesin and what does it do? What is dynein?
it is a plus end motor protein that generates force by coupling ATP hydrolysis to conformational changes
dynein is a minus end motor protein that does same thing
What are the microtubule motor proteins and what do they do?
kinesins and dyneins;
they move organelles across microtubules
Cell migration occurs how?
by a actin cytoskeleton that generates force
What is dynamic instability?
the rapid interconversion between a growing and shrinking state of microtubules
What is catastrophe?
the random loss of GTP cap that leads to rapid shrinkage in microtubule dynamic instability
What is rescue?
the regain of GTP cap that leads to rapid growth in microtubule dynamic instability
What is the function of cohesions?
hold sister chromatids together at the end of S phase
is a large protein complex that forms a ring around the sister chromatids
