final

endocrine signaling

endocrine cells release hormones into the bloodstream

paracrine signaling

local mediators (signals) diffuse through out extra cellular fluid to contact neighboring cells

autocrine signaling

seen in cancer cells. when cell releases signal and responds to its own signal

neuronal signaling

neurons deliver neurotransmitters to target cells over long distances

contact-dependent signaling

a membrane-bound signal in one cell binds to the membrane-bound receptor on another cell

effector proteins

dictate how the cell responds to a signal. this is how two different cells have different responses to the same signal.

what is another factor that determines the response of a cell

the combination of signals that it is receiving

what are examples of extracellular signal molecules

proteins or hydrophilic molecules

what does typical signaling pathway look like

extracellular signal is bound to receptor → intracellular signaling molecule is produced and the intracellular signaling pathway begins → effector proteins are activated → response of the cell

examples of effector proteins

enzymes, transcription factors, cytoskeletal protein

molecular switches

protein kinases and GTP-binding proteins

how do protein kinases work

add a phosphate group on to a switch proteins

how do protein phosphatases work

remove a phosphate group from switch protein

what are 2 kinds of protein kinases

1.) serine/threonine kinases

2.) tyrosine kinase

how do GTP-binding proteins work

a protein will be active if it has GTP bound to it. proteins have GTPase activity to hydrolyze the GTP into the inactive GDP form to control signaling

what are 2 kinds of GTP-binding proteins

1.) G proteins

2.) monomeric GTPases

G-protein-coupled receptors

the active receptor → activate the G protein → activates OR inhibits an enzyme or ion channel

enzyme coupled receptor

if the receptor is an enzyme: signal binds → receptor dimerize → activates catalytic domain on intracellular side of receptor

If the receptor is not an enzyme: signal binds → receptor dimerize → activates the receptor → activates the enzyme

ion channel-coupled receptors

signal binds to receptor → open channel → allows ions in

out of the 3 cell-surface receptors, which one is EGFR

enzyme-coupled receptor

how does RTK activation lead to intracellular signaling

signal binds to receptor → receptors dimerize → receptor tails autophosphorylate on tyrosine residues → intracellular signaling molecules bind to phosphorylated tails → some proteins help propagate signal and others function as scaffolds

Trace the MAPK signaling pathway

inactive Ras is bound to membrane → adaptor protein binds to phosphorylated tails of RTK → Ras GEF binds to adaptor protein → Ras GEF will now switch Ras’s GDP to GTP (from inactive to active) → Ras-GTP phosphorylates MAP Kinase Kinase Kinase → active MAP Kinase Kinase Kinase phosphorylates MAP Kinase Kinase → active MAP Kinase Kinase phosphorylates MAP Kinase → active MAP Kinase phosphorylates transcription regulators that can promote cell proliferation, survival, and differentiation