BIO 211 Lecture Notes - Lecture 3: Arrestin, Diglyceride, Lysosome
30 May 2018
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Prior to Week 3 Class 1 – pp. 832-849 – can skip “Feedback generates Ca2+ waves and
oscillations,” “Some G proteins directly regulate ion channels,” “Smell and vision depend on
GPCRs that regulate ion channels”
Know
• The basic structure of a GPCR
o Single polypeptide chain that threads back and forth across lipid bilayer 7 times\
o Deep ligand-binding site at center
o Cylindrical
• What stimulatory and inhibitory G proteins are
o Stimulatory → increase cAMP levels by activating adenylyl cyclase
o Inhibitory → decrease cAMP levels by inhibiting adenylyl cyclase
• How cAMP and cGMP are made and degraded, and the enzymes that are involved in
regulating these processes
o cAMP synthesized from ATP by adenylyl cyclase and degraded by cAMP
phosphodiesterase
o adenylyl cyclase
▪ large multipass transmembrane protein with catalytic domain on cytosolic
side of plasma membrane
• What AKAPs are
o A-kinase anchoring proteins (scaffolds)
o Bind to regulatory subunits and to a component of cytoskeleton or membrane of
organelle
o Also bind other signaling proteins to form a complex
• What CREB is
o Transcription regulator
o Cyclic AMP response element – binding protein
o Recognizes CRE
o When PKA is activated by cAMP, it phosphorylates CREB on a single serine
o Phosphorylated CREB recruits coactivator called CREB-binding protein to
stimulate transcription of target genes
o Can transform short cAMP signal into long-term change in cell
• What PIP2, IP3 and DAG are
o PIP2
▪ Phosphoinositide
▪ Present in small amounts on inner half of plasma membrane
o IP3
▪ By product of cleavage of PI(4,5)P2
▪ Inositol 1,4,5-triphosphate
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