L14 Flashcards

Question

what are the types of enzyme linked receptors

Answer 1

Receptor guanylyl cyclases Receptor serine/threonine kinase Receptor tyrosine-kinase Tyrosine kinase-associated receptors Receptor tyrosine phosphatase

Answer 2

Contain 2 Guanylyl Cyclase domains which convert GTP to cGMP. cGMP activates downstream kinases

Answer 3

1. Binding of ANP induces a conformational change in the receptor that causes receptor dimerization and activation. 2. The Guanylyl cyclase activity of the receptor generates cGMP. 3. Increased concentrations of cGMP activates other signalling molecules determining the response 4. Example of response: Atrial natriuretic peptide (ANP) relax vascular smooth muscle and dilate blood vessels (vasodilation)

Answer 4

Contain Serine-Threonine kinase domains which phosphorylate target proteins (similar to PKA)

Answer 5

1. first messenger binds to receptor Type II 2. Receptor Type I then binds forming a ternary complex with Type II and first messenger. 3. Type II receptor phosphorylates Type I, activating the Ser-Thr Kinase activity of Type I 4. Type I then phosphorylate target proteins (re SMAD proteins) 5. Example of response: TGFbeta mediated cell proliferation

Answer 6

regulate transcription of target genes

Answer 7

Contain tyrosine kinase domains which phosphorylate themselves/other proteins.

Answer 8

1. Binding of 2 molecules of insulin causes the receptor to dimerise. 2. Once the receptors dimerise, then they use their cytoplasmic tyr kinase activity to phosphorylate each-other at multiple tyrosine residues creating “phosphotyrosine motifs”. 3. These motifs recruit intracellular signalling molecules leading to the response 4. Example of response: insulin mediated glucose uptake and storage in liver and muscles

Answer 9

MAP kinase signalling pathway

Answer 10

RTKs activate Ras An adaptor protein docks on a particular phosphotyrosine on the activated receptor The adaptor recruits a Ras guanine nucleotide exchange factor (Ras-GEF) that stimulates Ras to exchange its bound GDP for GTP The activated Ras protein can now stimulate several downstream signaling pathways Ras activates MAP-kinase kinase kinase MAP-kinase kinase kinase activates MAP-kinase kinase MAP-kinase kinase activates MAP-kinase MAP-kinase can change protein activity or gene expression

Answer 11

Ras protein contains a covalently attached lipid group

Answer 12

The receptors do not contain kinase domains. Instead, tyrosine kinase proteins are associated non-covalently with the cytoplasmic domains

Answer 13

1) Binding of first messenger to the receptor, induce a conformational change that cause dimerization of the receptor 2) The dimerization causes activation of the associated Tyr kinases (E.G. JAK2). 3) These kinases then phosphorylate tyrosine residues on both themselves and the receptor, creating “phosphotyrosine motifs” (Like the Tyr-Kinase receptors). 4) These motifs recruit intracellular signalling molecules leading to the response (re STAT proteins) 5) Example of response: cytokines signalling pathways (IL-6 acute phase response)

Answer 14

the receptors contain tyrosine phosphatase domains and remove Tyr residues to deposphorylate target proteins (For instance Tyr residues created by Tyr kinase receptors signaling)

Answer 15

1. 1st messenger binding to the receptor inducing a conformational change that activates the Tyr phosphatase activity of the receptor. 2. Target proteins are dephosphorylated by Tyr phosphatase activity 3. This causes phosphorylation of downstream proteins (for example Lck and Fyn) 4. Response example: CD45 induces the maturation of lymphocytes via binding to this receptor

Answer 16

Tyrosine kinase associated receptor

Answer 17

receptor tyrosine phosphatase

Answer 18

receptor guanylyl cyclase