Signal Transduction Flashcards
steroid hormones
intracellular receptors, lipophilic, can pass through membrane unaided
FOUND IN CYTOPLASM
cell surface receptors
embedded in plasma membrane of cell and face extracellular space
intracellular/ nuclear receptors
found in cytoplasm/ nucleus, bind to membrane-soluble ligands
contact dependent
requires physical contact of the two cells
endocrine system
signal producing cells release signaling molecules that act on taget cells
paracrine
signal producing cells release signaling molecules that act on proximal target cells
synaptic
neurotransmitter signaling @ synapses
phosphorylation=
on
dephosphorylation=
off
receptor tyrosine kinases
largest class of enzyme coupled receptors
most extracellular signals for growth, survival, and proliferation
SH2 domain
recognizes phosphorylated tyrosines
bind phosphorylated tyrosines
general mechanism enzyme coupled receptors
ligand binds, bringing subunits together=dimerization
-leads to phosphorylation of tyrosines on RTK
GTP
on
GDP
off
phosphorylated PKB
increases glcose uptake and glycogen synthesis
RTKs activating PI3
induces protein synthesis to regulate glucose transport and glycogen synthesis
-PI3 activated instead of RAS
receptor serine/threonine kinases
TGF-B binds, dimerization/ phosphorylation occurs
-SMAD complex moves to nucleus and regulates gene expression
-SMAD is mediator !!
cytokine receptors
DO NOT HAVE INTRINSIC KINASE ACTIVITY
associated w JAK kinase
receptors for signaling molecules that control growth and differentiation of leukocytes
JAK
tyrosine kinase, recruits STAT
STAT
mediator of signal for cytokine receptors
TNF receptors inactive when
if ligand absent, Ikb binds NFKb= inactive
thyroid hormones
FOUND IN NUCLEUS
An inhibitor of RAF would prevent the activation of what molecule
MEK
