3 Hormone Action pt 2 Flashcards
(34 cards)
what makes non-classical peptide hormones non-classical?
they’re not secreted directly into circulation; most likely secreted by various cells rather than a particular endocrine organ
what are examples of non-classical peptide hormones?
adipokines (like leptin)
list the types of non-classical hormones (4)
- peptide hormones
- amino acid derivatives
- lipid hormones
- metabolites
what are examples of non-classical amino acid derived hormones?
neurotransmitters: melatonin, serotonin, histamine
what makes non-classical lipid hormones non-classical?
they have membrane receptors instead of nuclear ones
what are examples of non-classical lipid hormones?
eicosanoids
what are some examples of non-classical metabolites that act as hormones?
lactate, ketone bodies
what can happen when there’s a mutation of a receptor’s gene sequences?
disorders/disease
what kind of receptors do steroid and thyroid hormones bind to?
nuclear receptors
where are the receptors for steroid and thyroid hormones located?
intracellularly in the cytoplasm or nucleus
how do the receptors of steroid and thyroid hormones work?
they act as transcription factors; must be able to read/bind to DNA and recognize certain sequences of nucleotides.
response of nuclear receptors is (fast/slow) compared to ligand binding receptors. why?
slow; transcription and translation of proteins is necessary
true or false: there are nuclear receptors capable of binding metabolites
true
what are the receptors called that can bind fatty acids?
PPARs; they have alpha, beta, and gamma isoforms.
ligands of nuclear receptors are _____ soluble
lipid
why is it easier to make synthetic ligands for NRs? implications?
all ligands for NRs are lipid soluble and small, making it easy for them to diffuse through cell membranes.
shows huge potential in medicine for treating cancers
how do NRs contribute to metabolism when bound to metabolites?
the NRs can act as metabolite sensors that lead to transcription and translation
what mechanisms are available that can regulate ligand levels?
- precursor
- synthesis
- secretion
- activation (receptor function)
- deactivation
- elimination
what happens when a NR ligand isn’t hydrophobic enough to diffuse through the nuclear membrane?
requires a carrier protein that will separate once inside
what’s an example of a NR ligand that needs the help of carrier proteins?
bile acids
what happens once the ligand binds to a NR receptor?
receptor becomes active and starts modulating transcription of target genes to mRNA to translate into proteins
true or false: every domain of different nuclear receptors are unique to their receptor
false - all nuclear receptors have domains in common
what significant domains to NRs have in common?
- DNA-binding (DBD)
- Nuclear localization signal (NLS)
- Ligand Binding domain (LBD)
what sequence do steroid receptors usually bind to?
AGAACA
