biotech lecture 5 (minden 4) DIYA FAKE

signaling steps

reception, transduction, response

how cells respond to signals

growth, proliferation, survival, differentiation, death

types of cell signaling

autocrine: receptor activated by its own ligand

paracrine: cells ligands affect nearby cells receptors

endocrine: travel thru body (blood) to other receptors (hormones)

contact dependent: membrane bound signaling molecule (cell) binds to target cell at receptor

synaptic: neurotransmitter released at synapse to go to target cell

receptor categories

enzyme linked receptors (RTKs), GPCRs. intracellular receptor, gated channels

ligands

mostly hydrophilic so can't cross membrane and instead bind to cell surface receptors

hydrophobic ligands can cross membrane and bind to internal receptors

kinases

an enzyme that catalyzes the transfer of a phosphate grp to its substrate; phosphorylate their substrate; often P added to OH grp of amino acid

protein kinases

serine/threonine kinases: phosphorylate proteins on these amino acids --> resulting called phospho-serine/ phospho-threonine

tyrosine kinases. --> phospho-tyrosine

dual specificity kinase: can phosphorylate their substrate on serine, threonine, and tyrosine

kinase cascade

enzymes activated by phosphorylation and these enzymes can include kinases; amplification of a signal each kinase activates the next one

lipid kinases

important for cell signaling; ex: PI3 kinase (PI3K) phosphorylates the membrane lipid phosphoinositide (PI)

when bound to GTP

active

when bound to GDP

inactive

2 types of GTP binding proteins

large heterotrimeric GTP binding proteins and small monomeric GTP binding proteins

adapter proteins and various proteins have

interaction domains

interaction domains

cause proteins to interact with each other; sh2, ptb, sh3, ph domains

sh2 domain

binds phospho-tyrosine

ptb domain

binds phospho-tyrosine but with a different specificity

sh3 domains

binds to proline rich domains

ph domains

binds to phosphorylation sites on phosphoinositides (PIs)

adapter proteins

proteins that bind to each other but do not have any other activity