B3 PR Flashcards
What is autocrine signaling?
Signaling that is sent and received by the same cell
What is paracrine signaling?
Signaling that is sent and travels a far distance
What is endocrine signaling?
Signaling that is carried through the bloodstream
What is juxtacrine signaling?
Signaling that is carried between cells that are in contact with one another
What is the role of a protein kinase?
To transfer a phosphoryl group from ATP to a substrate protein that contains Ser, Thr, Tyr, His or Arg
What is the role of protein phosphatase?
To remove the phosphoryl group
What is prolactin?
It is a hormone that triggers milk production in the mammary gland of women after child birth
What are the steps of the JAK-STAT pathway?
- Prolactin (ligand) binds to the receptor
- Receptors dimerize
- JAK2 is phosphorylated
- The Tyr on STAT5 is phosphorylated
- STAT5 enters the nucleus and leads to transcription
What is a GEF?
A guanine exchange factor which is a recruiter and activates GDP by converting it to GTP
What is a GTPase?
Stimulate the hydrolysis of GTP and inactivate the protein by converting it to GDP
What is a GDI?
Inhibits the release of GDP so it remains the inactive form which is GDP
What are the steps of the general MAP kinase cascade?
- A ligand binds to the RTK
- Phosphotyrosines on the receptor resulting from tyrosine kinase activity acts as binding sites for SH2 proteins
- SOS (GEF) activates Ras by exchanging GDP -> GTP
- Ras leads to the Raf activation (MAPKKK) which starts the MAP kinase cascade
- MEK (MAPKK) is phosphorylated
- ERK (MAPK) is phosphorylated
- Transcription factors (Fos and Jun) enter the nucleus
- Transcription is initiated and MKP-1 (MAPK phosphatase) is made
What is PKA?
This is a protein kinase that is dependent on cyclic AMP to be activated
How does PKA impact the MAPK pathway?
cAMP activated PKA blocks the signals from Ras to Raf and inhibits MAPK activation
What is cyclic AMP?
It is a type of second messenger that leads to a wide variety of hormones and neurotransmitters
