Exam 2 Flashcards
Cell-cell communication
juxtacrine
endocrine
paracrine
synaptic
autocrine
juxtacrine: cell-cell contact
endocrine: hormones, low concentration, high affinity, stays long
paracrine: physically close together, high local concentration, low affinity binding, rapid
synaptic: nueronal, close synaptic, low affinity binding, rapid
autocrine: self, sender and target, low affinity binding, rapid
intracellular receptor
steroid - highly specific
thyroid - thyroid binds and dimerizes to promote DNA binding. signaling is effect of transcription
vitamin
4 major cell-surface receptors
ligand gated ion receptor, enzyme linked/ cytokine receptors, GPCRs, rtks
protein phosphorylation
induce conformational change, if enzyme is phosphorylated it will activate and react
cell signaling + receptor binding
rapid reduction level of message/agonist
receptor loss or desensitization
ligand gated ion channels
transmembrane ion channel
neurotransmitter binding to channel induces depolarization or hyperpolarization
receptor tyrosine kinase
enzyme linked receptor
phosphorylates itself
dimerizes to activate intracellular activity
extracellular domains have various families
RAS/MAP3K cascade
RAS
activating protein is GEF and GRB2
activated RAS triggers MAP3K cascade
has conformational change depedning on GDP or GTP bound
GPCRs
no enzyme activity
GEF: release of GDP is naturally slow so GEF increases GDP rate of release. Responsible for G protein activation
GPCRs Heterotrimeric
Ga, Gb, Gy
Ga has GTPase activity
cytokines
controls growth of activity of immune system cells and blood cells to execute inflammation
pleiotropic
same cytokines produce similar effects
Cytokine types
IL: secreted by leukocyte and acts on inflammatory response
chemokine: chemotactic activity like cell migration
TNFa: released upon infection by macrophages
Interferons: regulates signalling for virus/bacteria
Cytokine receptor
overly expressed tumor cells
IG: expressed everywhere, present throughout several cells
IL 17: little structural homology w/ cytokine receptors
TFNa
TFN: cysteine rich extracellular binding
chemokine receptor
associated w/ immune disease and
CXCL8: chemokine secreted by macrophage that directs neutrophils
selectin
weak reversible binding for sialyl-lewis X carbs for rolling adhesion
ICAM-1
recruitment is mediated by cell-adhesion.
exhibits tight binding
Type 1 + Type 2
pleiotropic and involve multiple recepter chains
PI3K/Akt
anti-apoptotic
JAK-STAT
signal transduction, activate transcription, transfers signal from cell membrane to nucleas
RAS-MAPK
mitogenic cell proliferation
causes more cells
Ga
activiation occurs on here
Gai
inhibits adenyl cyclase and camp and pka
pka involved in glycolysis and gluconeogensis
Gas
stims adenyl cyclase and camp and pka
pka involved in glycolysis and gluconeogensis
Gq
PLC converts PIP2 to DAG and IP3
IP3 goes to IP3 to Ca2+
DAG goes to PKC
G protein signal termination
GTPase converts GTP to GDP very slowly
RGS speeds this process up.
DNA melting
regulatory step to seperate 2 DNA strands and initiate replication
licensing
permitting proteins at origin or replication to being DNA replication
licensing must be limited to once per cell cycle
MCM
mini chromosome maintenance complex
replication preinitiation
CTD1 + CDC6 recruited to form preiniation complex
phosphorylation: releases CDC6 and CDT1 activated MCM helicase and phosphorylated form can no longer license the start of second round of DNA replication
after licensing factors are released
