ppwt 3 Flashcards
what is the process of Hormone action
extracellular signal molecule binds to receptor protein -> intracellular signalling protein -> target protein
what are the 2 types of recptors
pathways with cell surface receptor and pathways with intracellular receptor
where is the receptor found for
hydrophilic hormones
hydrophobic hormones
hydrophilic : cell surface
hydrophobic: intracellular receptor
what are the rules and exceptions for lipids hormones prostaglandins and leukotrienes
they have cell surface recptors instead of nuclear reco
what is the basic structure of a cell surface recptor
- ectodomain - hormone bind, rich in cysteine residues
- hydrophobic transmenbraine - in th elipid billayer
- cytoplasic domain - relays signal and induce a signaling cascade
true or false
does cytoplasmic domain indeuce a signaling cascade
true
what are the 3 protiens that are modulated by phosphorylation
serine, threonine and tyrosine
explain the process by which proteins are modulated by phosphorylation
- an inactive protein is activated by protein kinase and ATP->ADP. Their OH will be transformed as P
- the activated protein will serve as enzymes for other activation of protein
which phosphorylated amino acids are more abundant
serine and threonine are more abundant than tyrosine
what are the 3 types of cell surface receptors
- G protein coupled receptor (GPCR)
- Tyrosine kinase receptor (RTK)
- serine threonine kinase receptor (RSTK)
explain the GPCR
- epinephrin binds to its specific receptor
- GDP is replaced to GTP in the Gs coupled receptor
- Gs alpha binds to adenylyl cyclase
- adenylyl cyclase catalyses the formation of cAMP
- cAMP activates PKA
- pka will cause a cellular response to epinephrine
- with the enzyme cyclic nucleotide phosphodiesterase cAMP is degraded and there is no PKA activation
what are the 2 parts of PKA
catalytic subunit and the regulatory subunit
what happens to pka when 4 camp binds to it
the catalytic subunit cleft will be available
explain the pathway of signal control - desensitization and desensitization cycle
- binding of epinephrine to beta-adrenergic receptor triggers dissociation of Gsbeta gamma from Gs alpha
- Gsbeta gamma recruits Bark and it phosphorylates SER residues at the carboxyl terminus of the receptor
- B arrestin (Barr) binds to the phosphorylated carboxyl-terminal domain of the receptor
- receptor arrestin complex enters the cell by endocytosis
- arrestin dissociates, receptor is dephosphorylates and returned to cell surface
explain what is the function of Gs alpha?
activates adenylate cyclase