Cell Bio Chapter 18

Which of the following is NOT one of the three main types of membrane receptors found in most eukaryotic cells?

soluble receptors

The gas nitric oxide (NO) can bind to an receptor tyrosine kinase (RTK) in the cell membrane.

False

The influx of ions through gated ion channels usually leads to a change in membrane potential.

True

Gated ion channels are typically found in neurons and muscle cells.

True

GPCRs are structurally ___ and functionally ___ .

similar, diverse

GPCRs represent the largest family of cell membrane receptors in all eukaryotes.

True

Unlike GPCRs, enzyme-coupled receptors do not activate heterotrimeric G-proteins when activated.

True

Each RTK monomer possesses an intracellular ___ domain.

tyrosine kinase

The binding of an extracellular chemical signal to a GPCR leads to ___ of a ___ .

activation, heterotrimeric G-protein

GPCRs are single-pass transmembrane proteins that are woven into the membrane during translation.

False

When a heterotrimeric G-protein binds GTP, what happens to its subunits?

the α-subunit dissociates from the β/γ-complex

The β-subunit of a heterotrimeric G-protein is directly connected to the cell membrane.

False

When acetylcholine binds to a GPCR on a heart cell membrane, ___ channels ___.

K+, open

The ion channels in a heart cell membrane are activated by the α-subunit of a heterotrimeric G-protein in response to the binding of acetylcholine to a GPCR.

False

The two most common cell membrane-bound enzyme targets of heterotrimeric G-proteins are adenylyl cyclase (AC) and phospholipase C (PLC).

True

AC and PLC are activated by the same type of heterotrimeric G-proteins.

False

When active, adenylyl cyclase produces:

cAMP

In a GPCR-mediated signal transduction pathway that involves adenylyl cyclase (AC), when does the signal first begin to diffuse throughout the entire volume of the cytosol?

after the activation of AC

Phospholipase C (PLC) is a cell membrane-bound enzyme.

True

PLC cleaves ___ into ___ and ___

PIP2, IP3, DAG

Which of the following is secreted by the pancreas in response to low levels of glucose in the blood?

glucagon

Which of the following is activated in response to low levels of glucose in the blood?

protein kinase A (PKA)

The binding of an extracellular chemical signal to one or both RTK monomers results in ___ of the extracellular domains.

dimerization

Regardless of the type of RTK, each RTK monomer binds one extracellular chemical signal.

False

The activation loop blocks the:

ATP-binding site

During trans-autophosphorylation, each monomer phosphorylates itself.

False

SH2 and PTB domain-containing proteins bind to phosphorylated ___ residues within the ___ of activated RTKs.

tyrosine, C-terminal tail

Once an RTK dimer is fully active and phosphorylated, the signal transduction pathway will diverge into two.

True

In epidermal growth factor-mediated signal transduction, the phosphorylated RTK C-terminal tails directly recruit:

Grb2

MAPKK phosphorylates:

MAPK

Ca2+ is used in GPCR-mediated signal transduction but not in RTK-mediated signal transduction.

False

What is the major Ca2+ binding protein (CBP) in virtually all eukaryotic cells?

CaM

CaMKII is thought to be involved in metabolism and digestion.

False

It is common for the signal transduction events of a GPCR-mediated pathway to interact with events of an RTK-mediated pathway.

Tru

While a Heterotrimeric G-protein is activated by an
extracellular signaling molecule binding to the
GPCR, which of the following would you expect to
see?

GTP is bound to the α-subunit.

The α-subunit separates from the β/γ-complex.

In the brainstem, which controls reflexes such as
vomiting, the extracellular signal Substance P
binds to a GPCR and triggers vomiting.
Interestingly, this pathway works through Gq and
Gs proteins. This means it _____.

activates both adenylyl cyclase and phospholipase C

n an attempt to prevent chemotherapy-induced
vomiting, a new drug called Rolapitant has been
developed. Remembering that the extracellular
signal Substance P binds to a GPCR and triggers
vomiting, how can Rolapitant prevent vomiting?

By preventing substance P from binding to the GPCR

Pick out all of the molecules that are commonly
found in the PLC pathway:

PKC

DAG

During the adenylyl cyclase signaling pathway, the
effector protein ____ generates ____ which
activates ______, causing downstream
phosphorylation.

adenylyl cyclase, cAMP, PKA

During RTK activation, _____ of the extracellular
and intracellular domains allows the ____ of the
activation loop, so that ____ can occur at the C-
terminal tails.

dimerization, trans-autophosphorylation, recruitment

In epithelial secretory cells, Ca2+ signaling and the
Adenylyl cyclase pathways cross talk. In one instance, PKA phosphorylates the IP3 receptor on the ER membrane, making it more responsive to IP3. In this case, _____ calcium would be released when the PLC pathway is activated, maximizing the secretion.

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