Cell Signaling II Flashcards

Flashcards based on Cell Signaling II lecture notes.

What are the key proteins involved in GPCR signal termination?

G-protein coupled receptor kinase (GRKs), Arrestins, Regulator of G protein signaling (RGS) proteins, and phosphodiesterases.

What is desensitization/adaptation in cell signaling?

Reduced outcome in response to a prolonged stimulation.

How do GRKs contribute to the termination of G-protein-coupled signaling?

G protein-coupled receptor kinase (GRK) phosphorylates GPCRs.

What is the role of arrestins in GPCR signaling termination?

Arrestins bind to phosphorylated GPCRs, leading to receptor-mediated endocytosis.

What is the result of receptor-mediated endocytosis of GPCRs?

Internalization of GPCR to terminate the signal.

What is the role of GTP hydrolysis in cell signaling?

GTP hydrolysis shuts signaling off.

Name three second messengers in cell signaling besides cAMP.

DAG, IP3, and Ca2+.

What molecules are generated by the cleavage of PIP2 by PLCb?

inositol 1,4,5 triphosphate (IP3) and diacylglycerol (DAG)

How can changes in cytosolic Ca2+ be achieved?

Influx of Ca2+ through open channels in the plasma membrane OR release of Ca2+ from internal Ca2+ stores such as from IP3 receptors

Name 3 functions of Calcium Binding Proteins

affect a number of different types of cellular effectors, including protein kinases, activate or inhibit various enzyme and transport systems, change the ionic permeability of membranes induce membrane fusion, alter cytoskeletal structure and function.

Name receptor classes

G-protein coupled receptors (GPCR), ligand-gated channels (ionotropic receptors), receptor protein tyrosine kinases (RTK), steroid hormone receptors (nuclear receptors)

What is the primary function of protein-tyrosine kinases (RTKs)?

phosphorylate tyrosine residues on target proteins.

What do RTKs ligands primarily consist of?

Growth factors and hormones

Why is dimerization needed for RTK activation?

Ligand binding leads directly to dimerization of the receptor and activation of its kinase activity

How is the insulin signaling relayed?

Activated insulin receptor recruits insulin receptor substrate proteins (IRSs). Through IRSs, a variety of signaling pathways can be activated.

What are the two types of diabetes mellitus and what are caused by?

Type 1 is caused by defects in insulin production and Type 2 diabetes is caused by gradual insensitivity to insulin.

What is the function of Sos in the Ras/MAPK pathway?

Sos activates Ras. Acts as a guanine nucleotide exchange factor.

What is the result of the MAP kinase cascade?

activation of transcription factors which leads to cell growth and proliferation

Describe signal convergence.

Signals from unrelated receptors lead to activation of a common effector.

What is signal cross-talk?

Signals can be passed back and forth between pathways

Name ligands that bind to intracellular receptors.

estrogen, testosterone, retinoic acid, vitamin D etc