Cell Communication Flashcards
(22 cards)
what are the three stages of cell signalling
- receptor activation
- signal transduction
- cellular response
what is receptor activation
the binding of a ligant causes a conformational change in a receptor that activates its function
what is signal transduction
the activated receptor stimulates a series of proteins that forms a signal transduction pathway
what is a cellular response
the signal transduction pathway affects the function and/or amounts of cellular proteins
what are enzyme-linked receptors and what is their process
- relay proteins
- protein kinase cascade - transcription factors activated - genes expressed and protein synthesis
what are receptor tyrosine kinases and what do they do
enzyme-linked receptors
- recognize various ligands and move phosphates around
what is the g-protein coupled receptor series of events
activation of g-protein, production of cAMP, activation of PKA, and activation of proteins
what are g-proteins? why are they needed
- links the 1st and 2nd messengers together and is activated when a ligand binds to a receptor at the membrane surface
what are the 1st and 2nd messengers
1st: when a ligand binds a cell surface receptor in plasma membrane
2nd: cyclic AMP; acts in the cytoplasm
what is amplification
when a small number of signal molecules (ligands) bind to membrane receptors (secondary receptors)
what is serotonin an example of? what is the general series of events
- speeds up the speed of communication (causes amplification)
- signal molecules bind to a g-protein coupled receptor which causes activation of the g-protein
- GTP and the activated g-protein attach to an andenylyl cyclase and promotes the synthesis of cAMP from ATP
- cAMP activates PKA by binding to the subunits; this releases active catalytic subunits of PKA
- PKA uses ATP to phosphorylates proteins which causes a cellular response
what is epidermal growth factor an example of and what is the series of events?
- enzyme-linked receptor; stimulates cell growth or division
- 2 EGF molecules bind to the receptor subunits and causes them to phosphorylate (change confirmation)
- the phosphorylated receptors are recognized by the first relay protein which changes confirmation so it can interact with the other relay proteins
- the protein kinase cascade happens (the last relay protein activates a protein cascade where sequential protein kinases are activated
- this is ended with the phosphorylation of an Erk protein
- Erk enters the nucleus and phosphorylates Myc and Fos
- the cell responds to these transcription factors and responds accordingly
what does the phosphorylation of proteins cause?
produces a cellular response; it will either activate or inhibit proteins
what are the 5 types of cell-to-cell communication
- direct intercellular
- contact-dependent
- autocrine
- paracrine
- endocrine
what is direct intercellular communication
- signals pass through gap junctions from the cytosol
what is contact-dependent cell communication, example
- membrane-bound signals bind to receptors on adjacent cells
- MHCII and TCR
what is autocrine communication, example
- cells release signals that affect themselves and nearby target cells
- t cells activating an inflammatory response with IL-2
what is paracrine communication
- cells release signals that affect nearby target cells
what is endocrine communication
- cells release signals (hormones) that travel long distances to affect target cells
what is an enzyme
alter metabolism or other cell functions
what are structural proteins
alter cell shape or movement
what are transcription factors
alter gene expression, which changes the types and amounts of proteins in the cell
