BICD 110 Lecture Notes - Lecture 14: Jolla, Phospholipid, Diglyceride
28 Jun 2018
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BICD110 Lecture 14 Notes 5/22/18
- Different signals are used for different purposes
oAdrenaline tells cells to break down glycogen, survive, divide, differentiate, die, change
shape, move, or mate
- How to reverse signal of ligand
o1) Alpha GTP subunit hydrolyzes GTP to GDP, increasing its affinity to beta and gamma
subunits
o2) Desensitize receptor, causing it to become inactive
o3) Break down cAMP to 5’AMP using cAMP phosphodiesterase
Caffeine, theophylline (tea), and theobromine (chocolate) inhibit
phosphodiesterase, so you stay in a more aware state
o4) Dephosphorylate proteins using protein phosphatase
Common: protein phosphatase 1
- Molecular basis of beta-adrenergic receptor
oHas 7 transmembrane domain; the ligand binds within the domain, in the membrane
Charged residues through transmembrane, which face inward, recognize the
adrenaline ligand, allowing the ligand to bind within the membrane
oG protein coupling occurs at 3rd loop and some of C terminus
oReceptor desensitization occurs when PKA phosphorylates AAs in 3rd
loop and C terminal where the G protein would normally bind. This
prevents binding, so the cell doesn’t respond to the signals present.
Protein phosphatase 1 turns it on again after time, so if you still have
adrenaline, you can still activate fight or flight response
- Other examples of GCPRs
o7 transmembrane receptors for: adrenaline, serotonin, light (rhodopsin), taste receptors
for bitter and sweet, smell, pheromones, and histamines
- Different heterotrimeric G proteins have different purposes
o1) Gs: stimulatory; present in all cells
stimulates AC and can activate certain calcium channels
alphas, betas, and gammas subunits
cholera toxin locks alpha subunit as GTP-alphas, keeping signal constantly on
discovered by Al Gilman; won 1994 Nobel Prize
o2) Gi: inhibitory; present in all cells
inhibits AC
turned on by different receptors
alphai, betai, and gammai subunits
o3) Gt: transducin; only in photoreceptor cells in eyes
inhibits cGMP phosphodiesterase, to decrease cGMP
rhodopsin (GCPR receptor for light) activates transducin (G protein for rhodopsin) to
activate another effector
o4) Golf: olfactory
discovered by Linda Buck and Richard Axel; won 2004 Nobel Prize
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Different signals are used for different purposes: adrenaline tells cells to break down glycogen, survive, divide, differentiate, die, change shape, move, or mate. Caffeine, theophylline (tea), and theobromine (chocolate) inhibit phosphodiesterase, so you stay in a more aware state: 4) dephosphorylate proteins using protein phosphatase. Molecular basis of beta-adrenergic receptor: has 7 transmembrane domain; the ligand binds within the domain, in the membrane. This prevents binding, so the cell doesn"t respond to the signals present. Protein phosphatase 1 turns it on again after time, so if you still have adrenaline, you can still activate fight or flight response. Other examples of gcprs: 7 transmembrane receptors for: adrenaline, serotonin, light (rhodopsin), taste receptors for bitter and sweet, smell, pheromones, and histamines. Discovered by linda buck and richard axel; won 2004 nobel prize. Mice have 1000 genes and 300 pseudogenes that contain these. Humans have 350 genes and 750 pseudogenes. Whales have 12 genes and 988 pseudogenes.
