Endo, Topnotch Flashcards
(72 cards)
Etymology of “hormone”
Hormaein meaning to arouse
Hormone classes (3)
1) Steroid
2) Protein
3) Tyrosine derivatives
Hormones that induce production of new protein from DNA
Steroid
Hormones that modify existing proteins
Protein hormones
Tyrosine-derived hormones (4)
1) NE
2) Epinephrine
3) T3
4) T4
T/F Thyroid hormones are lipid-soluble
T
G protein subunits
α, β, γ
G protein-coupled receptors are activated by
GTP
GTP is activated by
Guanine nucleotide exchange factors (GEFs)
GTP is inhibited by (2)
1) GTPase-accelerating proteins (GAPs)
2) RGS proteins (regulator of G protein signaling)
G protein subunit bound to GDP
α
Sequence of events upon binding of hormone to extracellular portion of G protein-coupled receptor
1) GDP > GTP
2) α-subunit dissociates from trimeric complex to associate with other signaling proteins
3) Signaling process terminated with removal of bound hormone
4) α-subunit inactivates itself
5) GTP > GDP
6) α-subunit combines with β- and γ-subunit
Signaling proteins associated with α-subunit alter activity of (2nd messengers)
1) Ion channels
2) Adenylyl cyclase
3) Phospholipase C
Activity of adenylyl cyclase
ATP > cAMP > activation of protein kinase A > downstream phosphorylation
Activity of phospholipase C
PIP2 (membrane phospholipid) > IP3 + DAG
Activity of IP3
Mobilizes Ca from mitochondria and ER > smooth muscle contraction or cell secretion
Activity of DAG
Activates PKC > phosphorylation of downstream proteins
2nd messenger that is the precursor of PGs and other local hormones
DAG
2nd messenger associated with αs- and αi-subunit
Adenylyl cyclase > cAMP > PKA
Activities of cAMP
1) Activation of PKA
2) Directly regulate ion channels
Enzyme for degradation of cAMP
Phosphodiesterase
αt-associated G protein is aka
Transducin
Activity of αt-subunit
Activates cGMP PDE > decreases cGMP > closes cGMP-dependent ion channels
α-subunit associated with phospholipase C
αq-subunit
