Chapter 7

Question 1

signaling receptors typically located on the cell surface generally do what?

Answer 1

initiate signaling in the cytosol,

followed by a nuclear phase.

Question 2

what is the most prominent category of immune receptors contributing to innate and adaptive immunity?

Answer 2

immune receptors that
belong to a receptor family in which non-receptor
tyrosine kinases phosphorylate tyrosine-containing
ITAM motifs on the cytoplasmic tails of proteins in
the receptor complex

Question 3

Antigen receptors use coreceptors to do what?

Answer 3

s to enhance signaling. Coreceptors bind to the same antigen
complex that is being recognized by the antigen
receptor

Question 4

how can signaling from antigen receptors be attenuated?

Answer 4

by inhibitory receptors

Question 5

The TCR complex is made up of what?

Answer 5

the TCR α and β
chains that contribute to antigen recognition and
the ITAM-containing signaling chains CD3 γ, δ,
and ε as well as the ζ homodimer. The CD3 chains
each contain one ITAM, whereas each ζ chain
contains three ITAM

Question 6

TCR ligation results in what?

Answer 6

n tyrosine phosphorylation of
CD3 and ζ ITAMs by Src family kinases and the
recruitment of ZAP-70 to the phospho-ITAMs,
each SH2 domain of ZAP-70 binding to one phosphorylated tyrosine of the ITAM

Question 7

activated ZAP-70 phosphorylates what?

Answer 7

tyrosine residues on adaptors, and downstream enzymes are

recruited to the signalosome

Question 8

Enzymes that mediate the exchange of GTP for
GDP on small G proteins such as Ras and Rac help
initiate what?

Answer 8

MAP kinase pathways. These pathways
lead to the induction or activation of transcription
factors such as Jun and Fos, components of the
AP-1 transcription factor

Question 9

Activation of PLCγ1 leads to the release of what?

Answer 9

IP3 from
PIP2, and IP3 induces release of calcium from
intracellular stores. Depletion of calcium from
intracellular stores facilitates the opening of CRAC

Question 10

what is CRAC?

Answer 10

a store-operated channel on the cell surface that
maintains the raised intracellular calcium levels.
Calcium binds to calmodulin and activates downstream proteins including calcineurin, a phosphatase that facilitates the entry of the NFAT
transcription factor into the nucleus

Question 11

when is Diacylglycerol generated?

Answer 11

in the membrane when
PLCγ1 releases IP3 from PIP2. DAG can activate
PKC-θ, which among other things can contribute
to NF-κB activation

Question 12

A lipid kinase called PI3-kinase converts PIP2 to

PIP3. PIP3 can do what?

Answer 12

recruit and activate PH domain–
containing proteins to the plasma membrane. PIP3
activates Itk in T cells and Btk in B cells. It activates
PDK1, a kinase that can phosphorylate a downstream kinase called Akt that mediates cell
survival

Question 13

Costimulatory receptors initiate signaling separately from antigen receptors, but signaling outputs
from antigen receptors and costimulatory receptors synergize where?

Answer 13

in the nucleus. The major costimulatory receptor in T cells is CD28

Question 14

T cell signaling can be inhibited by what?

Answer 14

phosphatases
that may be recruited by inhibitory receptors such
as CTLA-4 and PD-1

Question 15

T cell signaling is also attenuated by what?

Answer 15

ubiquitin E3

ligases that can contribute to the monoubiquitination and lysosomal degradation of activated signaling proteins

Question 16

The B cell receptor is made up of what?

Answer 16

membranebound immunoglobulin and an associated
disulfide-linked Igα and Igβ heterodimer. Both Igα
and Igβ contain ITAM motifs in their cytoplasmic
tails. Signaling pathways linked to the BCR are
broadly similar to signaling pathways downstream
of the TCR.

Question 17

The coreceptor for the BCR is what?

Answer 17

CD21, also known
as CR2 (complement receptor type 2)

Question 18

Attenuation of immune receptor signaling in B

cells, T cells, and NK cells, among others, is mediated by what?

Answer 18

inhibitory receptors that frequently contain
inhibitory tyrosine–containing motifs or ITIMs in
their cytoplasmic tails

Question 19

Another important mechanism of signal attenuation involves what?

Answer 19

the ubiquitination of signaling proteins by E3 ubiquitin ligases

Question 20

Cytokine receptors can be divided into a few broad

categories based on what?

Answer 20

structural considerations and

mechanisms of signaling

Question 21

Many cytokine receptors use non-receptor tyrosine kinases called what?

Answer 21

JAKs to phosphorylate transcription factors called STAT

Question 22

Some cytokine receptors such as those of the TNF

receptor family activate what?

Answer 22

either canonical or noncanonical NF-κB signaling.

Question 23

Canonical NF-κB signaling is activated downstream of many receptors, including what?

Answer 23

TNF receptor
family cytokine receptors, TLRs and IL-1R family
members, and antigen receptors. The pathway
involves activation of IKKβ in the IKK complex,
phosphorylation of the IκBα inhibitor by activated
IKKβ, ubiquitination and proteasomal degradation of IκBα, and transport of NF-κB to the
nucleus.