copy 3 Flashcards
(8 cards)
How does the process of GLUT4 receptors moving to the surface take place?
- Insulin binds to IR which causes it to change shape and activate tyrosine kinase domain.
- Tyrosine kinase domain then phosphorylates certain tyrosine substrate
- The activated IR tyr-k then phosphorylates PI3K, PDK-1, and AKT (protein kinase B)
- This siganling process allows the glut4 receptors to move from inside the cell to the cell membrane increasing glucose uptake.
How does the second messenger system activated by Gq take place?
- Hormone binds to GPCR (Gq) which in turn activates Phospholipase C
- Active phospholipase C hydrolyzes PIP2 into DAG and IP3
- IP3 combines with IP3 sensitive Ca+2 channels on the ER causing them to open and release Ca+2 from the ER
- This increase in intracellular Ca causes PKC to get translocated to the internal surface of the plasma membrane
- DAG then activates PKC, PKC phosporylates many protein substrates
How does the Calcium-Calmodulin Second Messenger System work and give me an example?
Ca 2+ binds to the protein calmodulin (CaM) which has four Ca 2+ binding sites. When three or four of these sites are occupied, CaM changes its conformation activating calmodulin-dependent kinases (Ca-CaM kinases, e.g., CaMKII) * Example: Activation of CaMKII can phosphorylate Thr 17 of phospholamban (PLB) found in the SR of muscle cells bound to the SR Ca-ATPase.
* PLB phosphorylation (by both CaMKII and PKA) causes dissociation of PLB from the SR Ca uptake system, enhances SR Ca 2+ uptake accelerating relaxation and increasing SR Ca 2+ content.
How does NO signaling work?
This action is triggered by an increase in calcium (Ca²⁺) from PLC signaling.
Increased Ca²⁺ activates nitric oxide synthase (NOS).
NOS converts arginine into citrulline and NO.
NO diffuses to
neighboring smooth muscle cells.
NO activates soluble guanylyl cyclase, converting GTP into cGMP.
cGMP stimulates protein kinase G (PKG).
PKG phosphorylates targets such as phospholamban (PLB), resulting in smooth muscle relaxation.
What are the hormones that uses cAMP, IP3, Steroid hormone, and other mechanisims as a second messenger?
What are the two subfamilies of the nuclear receptors?
- Receptors that bind steroid hormones.
- Receptors that bind Thyroid hormones, retinoic acid, and vitamin D.
How do steroid hormones bind to their receptors and elicit a response?
They are lipid soluble so they can easily pass through the plasma membrane
once inside, they bind to a receptor in the cytoplasm.
The hormone-receptor complex then travels into the nucleus and binds to HRE which is linked to DNA
once they bind, transcription occurs to form mRNA which is then translated into a protein.
What two things do glucocorticoids block in order to decrease inflammation?
transcription activator protein-1 (AP-1) and nuclear factor κB
