Exam 23: Mechanisms of Signal Transduction

In the presynaptic neuron,______ influx causes neurotransmitter release while in the postsynaptic neuron,______ enters the cell following opening of ion channels.

The complex of zinc and cysteine residues seen in the structure of steroid hormone receptors is referred to as a(an)______________ structural motif.

What happens when the GTPase activity of a G protein is blocked?

Glucocorticoids are thought to function as anti-inflammatory agents since they are able to stimulate the synthesis of what protein?

What is the primary target of releasing factors from the hypothalamus?

The structures of isoproterenol (left)and epinephrine are shown below.What is isoproterenol?

Amphetamine and mescaline are agonists of ____________,the neurotransmitter often considered a "pleasure agent."

InsP₃ binds to _______ channels in the endoplasmic reticulum while DAG activates ___________.

What neurotransmitter is involved with cholinergic synapses?

When a nerve cell terminates at a muscle cell,the action potential causes opening of _____ channels that results in muscle contraction.

A G protein is inactive when the _____ subunit is bound to __________.

Inside a cell,glucagon ultimately results in the phosphorylation of a wide variety of enzymes to control their activity.For each of the following enzymes that is phosphorylated in response to glucagon binding,explain what happens to its activity and why that is important (considering the pathway that the enzyme is in and the overall goal of glucagon). Acetyl-CoA carboxylase: Pyruvate kinase: Glycogen phosphorylase: Phosphofructokinase-2:

Which of the following signaling molecules activate the phosphoinositide second messenger system?

Which second messenger is produced as a result of nitric oxide binding?

Insulin activates glycogen synthase while glucagon inhibits glycogen synthase.Explain the intracellular mechanisms that are used to bring about this activity.

Which of the following pathways correctly shows how glycogen synthase is activated in response to the activation of IRS-1 by insulin binding?

Which of the following hormones binds to a receptor tyrosine kinase?

Like G proteins,the Ras protein binds _______ when in its active state which is hydrolyzed to ______ to convert the protein to its inactive state.

Most steroid hormones exert their effects by initial binding to which of the following receptors?

The enkephalins,along with $\beta$ -endorphin,bind to the opioid receptor,so named because the opiate drugs such as __________ bind to it with high affinity