Paracrine signaling is characterized by ligands that are a. produced by the cell itself. b. secreted by neighboring cells. c. present on the plasma membrane of neighboring cells. d. secreted by distant cells.

When a chemical signal binds to an intracellular receptor ... a) ... it leads to the activation of G proteins. b) ... causes the receptor-hormone complex to open or close ion channels. c) ... the cell reacts faster than when a chemical signal binds to membrane-bound receptors. d) ... it leads to the formation of mRNA. e) ... the chemical signal is usually a large, water-soluble molecule.

Binding EGF to the EGF receptor causes phosphorylation of tyrosines on the cytoplasmic tail of the receptor. Which of the following best describes the mechanism by which this phosphorylation activates downstream signaling complexes? Select one    A. Causes degradation of receptor by proteasome pathway   B. Causes EGF receptor to be internalized so it can interact directly with downstream signaling molecules   C. Tyrosine phosphorylation alters 3D structure of downstream signaling proteins causing them to change from an inactive to active conformation   D. Causes release of EGF from receptor   E. Alters the localization of downstream signaling partners in the cytoplasm

Hydrophobic signaling molecules act by a. binding to plasma proteins b. starting second messenger systems c. binding to receptors inside the cell d. starting action potentials

Differential effects of epinephrine and norepinephrine among cell types and across cell types is dependent on: (Select all that apply) a.) Capillary density b.) Nuclear receptors c.) Type of G-protein expressed d.) Receptor subtype expression

An extracellular signaling molecule binds to cell surface receptor. This cell surface receptor changes shape and activates a trimeric G-protein.  What kind of receptor is this? a) Ion-channel coupled receptor b) Receptor Tyrosine Kinase c) G-Protein coupled receptor d) All of the other answers are correct e) Enzyme-coupled receptor

In the RAD signaling pathway the EGF ligand binds the EGF receptor, this initiated a phosphorylation cascade that results in cell proliferation. Which of the following statements is correct: a. RAS protein is the sognal b. EGF ligand is the signal c. cell proliferation is the signal d. EGF receptor is the signal e. none of the above

You decide to investigate cell signaling of a pair of newly identified GPCRs, GPCR-W and GPCR-Z. Each binds the same ligand, but activates different downstream heterotrimeric G-proteins that act on adenylyl cyclase. You discover that ligand binding has opposite effects on adenylyl cyclase activity for each receptor. GPCR-W causes an increase in adenylyl cyclase activity, while GPCR-Z causes a decrease in adenylyl cyclase activity. You obtain a cell line expressing GPCR-W, GPCR-Z, the relevant G-proteins, and adenylyl cyclase. There is baseline adenylyl cyclase activity producing a baseline amount of cAMP. You embark on a research project to characterize the following mutations in the components of the signaling pathway. 2. Will each of the following mutations increase or decrease the levels of cAMP inside the cell upon adding the ligand to the cell culture? A mutation in GPCR-W that prevents G-protein activation? A mutation in GPCR-Z that prevents G-protein activation? A mutation in…

In the G protein signaling pathway, the 2nd messenger is: a. ATP b. GDP Oc. Cyclic GMP d. Cyclic AMP C

The receptor-associated proteins called G proteins... A. bind GTP. B.  can activate or inhibit an effector protein, e.g. adenyl cyclase. C.  interact with membrane-associated proteins to influence their function. D.  both a and b E.  a, b, and c