6 overview hormonal mechanisms Flashcards
what is the first precursor molecule in peptide hormone synthesis? what does it signal for?
preprohormone
‘pre’- hydrophobic signal peptide on N terminus: signals for further processing and packaging for exocytosis
what happens in post translational modification in peptide hormone synth?
protein folding, disulphide bonds, glycosylation, pre-signal cleavage
when does post translational modification happen?
whilst preprohormone transverses rER
how is the protein transported from RER to golgi?
via microvesicles
what type of hormone is in the golgi?
prohormone
what happens to the prohormone in golgi?
additional processing, further cleavage, packaging into secretory granules
what does the rate of peptide hormone release depend on?
rate of exocytosis
when is the peptide hormone released?
upon arrival of stimulus
what type of enzyme converts cholesterol into steroid hormones?
biosynthetic enzymes
what property does cholesterol have and what is the consequence of this?
lipophilic, can diffuse through lipid bilayer so no secretory granules needed-> hormone is not stored
what do steroid hormones bind to?
plasma carrying protein by weak reversible bonds because they are hydrophobic so are insoluble
how do you increase levels of steroid hormones?
by increasing level of synthesis
t1/2 of peptide vs steroid hormones
peptide: minutes
steroid: hours- days
what are peptide hormones susceptible to?
protease enzymes because they are free hormone
describe peptide hormone action
receptor molecules (cannot cross lipid bilayer) -> G protein and effector or tyrosine kinase leading to signal transduction physiological response- altered activity of enzymes or ion channels/ altered expression of proteins
