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What is 1 + 3?
hormone goes to distant target organs via bloodstream
hormone acts locally and diffuses into neighboring cells
hormone acts on same cell that produced it
bind to the receptor to block the hormone
a day in the life of a peptide hormone
synthesized in ER, transferred to Golgi, packaged in secretory vesicles... secretion!
premature form of protein hormone that is proteolytically clipped to generate mature form
sequence is proteolytically cleaved into hormone
hormone stored in cell and released in "bursts" when stimulated; allows large amount to be secreted in short time period
hormones secreted as they are synthesized (less common than regulated secretion)
how many amino acids does insulin have???
half-life of circulating peptide hormones
a few minutes :'(
some (a few) peptide hormones circulate bound to other proteins (ex. IGF-1)
lipids. DERIVATIVES OF CHOLESTEROL
1st and rate-limiting step of steroid synthesis
cholesterol -----> pregnenolone (formed in the inner membrane of peanut, shuttled back and forth between mitochondria and ER for enzyme stuff)
life after secretion (steroids)
btw, rapidly secreted with little storage; bind to plasma proteins usu. low affinity and nonspecific; specific binding proteins affect halflife and rate of elimination
elimination of steroid hormones
inactivating metabolic transformations OR excreted in bile or urine