Exam 13: Biochemical Signaling

Considering the same unidentified proteins discussed in the question 32 above (UPS-1 through UPS-3)what can you conclude from the following observations and the knowledge you gained in this chapter? OBSERVATIONS: 1)UPS-1 is capable of autophosphorylation. 2)UPS-2 becomes phosphorylated only when UPS-1 is phosphorylated. 3)UPS-2, when phosphorylated interacts with UPS-3 and activates the Ras protein. 4)Recombinant UPS-2 protein that has a mutation resulting in the replacement of tyrosine for serine in the binding region loses all function. 5)The proteins Jun and Fos are expressed at high levels in the presence of UPS-1,2,3.

Heterotrimeric G proteins I.consist of three subunits, G $\alpha$ , G $\beta$ , and G $\gamma$ . II.function as an autoinhibtory segment. III.can function as a mediator to adenylate cyclase activity. IV.are anchored to the cytoplasmic side of the membrane.

Matching -A release of _____ would result in the stimulation of the liver to synthesize glycogen.

Somatostatin I.inhibits the release of insulin. II.inhibits the release of glucagon. III.stimulates the release of insulin. IV.stimulates the release of glucagon.

Autoinhibition in the SH2 and SH3 domains

Scaffold proteins limit

Matching -A molecule that often functions as a second messenger is ______.

The $\beta$ cells of the islets of Langerhans secrete ______ in response to ______ glucose levels in the muscle and/or adipose tissue.

Ras is an example of I.a protein anchoted by prenylation. II.a heterotrimeric G protein. III.a kinase activated protein. IV.a GTP dependent protein.

Which of the following are activated either directly or indirectly by a heterotrimeric G protein subunit? I.phospholipase C II.Herceptin III.calmodulin (CaM)sensitive kinase IV.MAPK

Which of the following is always true of hormones?

Which of the following correctly states an essential step in the function of heterotrimeric G protein function?

Which of the following is (are)an advantage(s)of protein phosphorylation in regards to biochemical signaling? I.Phosphorylation is rapid and specific. II.Phosphorylation is enzymatically reversible. III.Phosphorylation can be amplified by cascade systems. IV.Phosphorylation results in covalent modification of enzymes.

Which of the following is (are)associated with cAMP binding to cAMP-dependent protein kinase A? I.cAMP binds to the regulatory subunits. II.Tetrameric regulatory subunits and catalytic subunits dissociate. III.Catalytic subunits phosphorylate multiple targets with specific serine and threonine residues. IV.cAMP is membrane bound via phosphoinositol attachment.

Matching -Cytosolic calcium ion levels are altered by the _____ signaling pathway.

Catecholamines mediate their effects through I.α-adrenoreceptors. II.β-adrenoreceptors. III.receptor tyrosine kinases. IV.monomeric G protein receptors .

Insulin binds to a receptor that I.is coupled to a G protein. II.possesses tyrosine kinase activity. III.possesses serine/threonine phosphatase activity. IV.interact with proteins homologous to Src

The $\alpha$ cells of the islets of Langerhans secrete _____ in response to ____ glucose levels in the liver.

Which of the following proteins has a structural motif called an "EF hand"?

Recently a researcher has discovered several unidentified proteins (UPS-1 through UPS-3)that are up regulated (produced in higher levels)by the cell in response to the inclusion of high levels of an artificial sweetener called "sugarish".The research ran a PAGE gel of the protein samples after the cells were treated with different concentrations of "sugarish" (0-5 nm).One sample was also treated with the detergent SDS.The results are shown below.Which of the following are possible conclusions given these results and the knowledge you have gained from this chapter? I.UPS-1 functions as a dimer. II.UPS-1 interacts with UPS-2. III.UPS-1 interacts with UPS-3. IV.UPS-2 interacts with UPS-3.