Endocrine System Flashcards
Which 2 receptors are linked to intracellular enzymes?
receptor tyrosine kinases and cytokine receptors
What are the ligands of kinase receptors?
hormones, insulin, growth factors
EGF stands for?
epidermal growth factor
FGF stands for?
Fibroblast growth factor
VEGF stands for
vascular endothelial growth factor
What is the structure for kinase receptors?
monomer inactive state
has an extracellular binding site domain, a transmembrane domain, and an intracellular kinase domain
What does Grb2 stand for?
growth factor receptor bound protein 2
What does MAP stand for?
mitogen activated protein
What is the activation process of a tyrosine kinase receptor?
- 2 EGF molecules bind
- Receptor rearranges conformation
- Conformational changes activate cytoplasmic tyrosine kinase domains and tyrosine phosphorylation of intracellular regions form SH2 binding sites
- Grb2 binds to phophorylated tyrosine residues and activate Ras-Map kinases cascade
- Cascade activates gene transcription factors
- Cell proliferation
Over expression of what facilitates the growth of breast cancer?
Human epidermal growth factor receptor 2
What does trastuzumab do?
inhibits her2 dimerization, prevents Her2-mediated signaling, treats breast cancer
Cytokine receptors don’t have intrinsic enzymatic activity but binds what instead?
intracellular tyrosine kinase known as a janus kinase or JAK
What are the ligands of cytokine receptors?
gamma-interferon
interleukins
growth hormone
tumor necrosis factor
What are antagonists against tumor necrosis factor?
Adalimumab and Etanercept
What does TYK2 stand for?
tyrosine kinase 2
What does STAT2 stand for?
signal transducer and activator of transcription 2
How are cytokine receptors activated?
- ligands bind and receptors dimerize, cross phosphorylation of kinases of the receptor occurs
- Phosphorylation and dimerization of STAT2
- STAT2 dimer is translocated to the nucleus
- STAT2 binds to DNA response element
- Gene transcription generates proteins
- cellular response
Steroid nuclear receptors
steroid hormones
intracellular receptor located in the cell
inactivate genes
produced by endocrine glands
Non-steroid nuclear receptors
non-steroid hormones
bind to receptors in the cytoplasm
directly activate genes
produces by nervous tissue
Where are steroid hormone located?
the cytoplasm
What are some ligands that are steroid hormones?
estrogen
progesterone
testosterone
cortisol
aldosterone
What is an antagonist for estrogen?
Tamoxifen
What is an antagonist for progesterone?
Mifepristone
What are some ligands that are non steroid hormones?
thyroid hormones
retinoic acid
Vitamin D
free fatty acids
Where are non-steroid hormones located?
the nucleus
What is an antagonist of peroxisome proliferator-activated receptor (PPAR)?
Clofibrate
What does OR stand for?
nuclear hormone receptor
what does RXR stand for?
retinoic acid receptor
How are nuclear hormone receptors activated?
- steroid binds to steroid receptor in cytoplasm
- receptor dimerization and is transported to the nucleus where it binds with co-activators
- receptor dimer complex binds to and activates hormone response element binding protein (HREBP)
- HEBP recruiters RNA polymerase to make mRNA
- mRNA is translated by ribosomes to proteins
- proteins alter cell function
How are non-steroid nuclear receptors activated?
- hormone enters the nucleus and binds to inactive heterodimer
- Co-activators displace co-depressors and activate receptor and activate HREBP
- HEBP recruits RNA polymerase to make mRNA
- mRNA is translated by ribosomes to proteins
- mRNA alters cell function
