test4 Flashcards
Enables proteins to bind to phosphotyrosines
SH2 or PTB domains
Enables proteins to bind proline-rich regions of proteins
golgi
The activity of the Sos protein
Ras-GEF
Constitutive Ras activity is associated with
cancer
associated with the inner nuclear membrane
intermediate filaments (lamins)
found at the cell cortex and within microvilli
actin filaments
the contractile ring is made of this
actin (and myosin)
forms actin bundles that can associate with myosin II
alpha-actinin
binds individual actin subunits, preventing assembly
thymosin
prevents actin:myosin cross-bridging
tropomyosin
nucleates new actin fiber formation on the side of existing fibers
Arp2/3 complex
binds individual subunits and speeds elongation
profilin
What does kinesin-13 do
it is a catastrophe factor that destabilizes microtubules
associate with the growing plus ends of microtubules
+Tips
What is the function of stathmin?
binds pairs of microtubule dimers, preventing polymerization
Associates with the minus ends and is found at the MTOC
gamma-TuRC
What nucleotide to tubulin proteins bind and what happens when it is hydrolyzed
alpha and beta bind GTP:GDP if beta tubulin binds GDP, the protofilaments/microtubules become less stable
What fluorescent dye is typically used for cell cycle analysis by flow cytometry (a DNA histogram)
Propidium iodide (PI)
Cyclin-Cdk complexes G-Cdk, G/S-Cdk, S-Cdk, and M-Cdk go with what cyclins and Cdk partners?
G-Cdk - Cyclin D ; Cdk4, Cdk6
G/S-Cdk - Cyclin E ; Cdk2
S-Cdk - Cyclin A ; Cdk2, Cdk1
M-Cdk - Cyclin B ; Cdk1
Mitogens signaling via Ras activate a
MAP kinase cascade
Which transcription factor stimulates delayed-response gene expression
Myc
How is Rb inactivated?
by phosphorylation
What might excessive mitogen signaling lead to?
Myc and p53-dependent cell cycle arrest or apoptosis
DNA double strand breaks activate which kinase?
ATM
UV-induced DNA damage induces which kinase?
ATR
How do Chk1/Chk2 destabilize the p53:Mdm2 complex?
phosphorylation of p53
How does p53 activation lead to cell cycle arrest?
Expression of the CKI, p21
What negative feedback mechanism regulates p53 levels?
p53 can transactivate the Mdm2 gene, leading to p53 oscillations in response to persistent DNA double strand breaks
cells responding to signaling factors they secrete themselves
autocrine signaling
different types of intercellular signaling
contact dependent, paracrine, synaptic, endocrine
positive feedback can generate
all or none responses
What are some cell surface receptors?
ion channel coupled receptors,
G protein coupled receptors,
enzyme coupled receptors
What are some intracellular receptors?
preformed signaling complex on a scaffold protein
assembly of signaling complex on an activated receptor
assembly of signaling complex on phosphoinositide docking
intracellular signaling proteins can act as molecular switches by?
GTP binding or phosphorylation
What are some mechanisms of receptor desensitization
receptor down regulation receptor inactivation receptor sequestrination inactivation of signaling protein production of inhibitory protein
How do G proteins work
ligands binding to GPCR activate G proteins
cAMP activates which enzyme?
PKA
What binding domain enables proteins to bind to phosphoinositides?
PH
How are RTKs activated?
by signaling proteins that cause dimerization and trans-autophosphorylation of RTKs
What are MAPK cascades?
central signaling pathways that regulates a wide variety of cellular processes
The PI 3 kinase pathway promotes what
cell survival and growth
What transmits info from extracellular chemical signals to the nucleus resulting in DNA transcription and expression of genes
JAK/STAT signaling
What happens in interphase?
cell grows and makes a copy of its DNA
What happens in M phase?
cell separates DNA into 2 sets and divides cytoplasm
What are the major control steps of the cell cycle?
start transition, G2/M, metaphase to anaphase
Activation of Cdk requires what?
a CAK - Cdk activating kinase
How is Cdk activity regulated?
by inhibitory phosphorylation and cyclin level changes
what are the phases of mitosis?
prophase metaphase anaphase telophase
what are the 3 types of microtubules?
astral kinetochore interpolar
major motor proteins of mitotic spindle
kinesins and dyneins
cohesins do what
regulate separation of sister chromatids
cytokinesis is driven by
an actin contractile ring containing myosin II
3 major types of cytoskeletal protein filaments
actin, microtubules, intermediate filaments
nucleation is what in the formation of cytoskeletal polymers
rate limiting step
critical concentration is
when steady state phase is reached
toxins that affect actin filaments
actin and tubulin
listeria moves by
polymerizing actin
smooth muscle does not express
troponin
microtubules are formed
by the polymerization of a dimer of 2 globular proteins
tubulin forms
microtubulin
which end of microtubules is more dynamic
positive end
rescue phase=
catastrophe phase=
growth phase
shrinking
kinesin moves to
dyneins move to
kinesins move to plus end dyneins move to minus end
cell projection is a
cell protrusion