Immune Receptors and Signal Transduction

Question 1

LAT

Answer 1

Integral membrane protein that functions as an adaptor (it gets phosphorylated and recruits phospholipase C (PLC) and the GADS adaptor

Question 2

ITAM

Answer 2

Are not ligand binders. Some immune receptors have signaling polypeptide chains that contain cytosolic ITAMS (immunoreceptor tyrosine-based activating motifs)

Question 3

Src family kinase

Answer 3

Get activated in both B and T cells…will hyperphosphorylate other stuff

Question 4

Syk family tyrosine kinase

Answer 4

Recognizes the 2 phosphorylated tyrosines in a single ITAM and the Syk tyrosine kinase has tandem SH2 domains that each bind to an ITAM phosphotyrosine

Question 5

Anergy

Answer 5

Not enough co-receptors binding….then eventually an immune response

Question 6

BRC vs TCR

Answer 6

BCR: lot of Ig

TCR: lot of alpha/beta chains

Question 7

PDK1 (comes from PIP3) phosphorylates and activates–>downstream Akt kinase–>helps w/ cell survival by inactivating Bcl-2 (apoptotic protein)

Answer 7

True

Question 8

MAP kinase cascade is downstream of TCR activates AP-1–>major switching TF

Answer 8

True

Question 9

NFkB

Answer 9

Upon signaling, an IkK gets activated and phosphorylates IkB and this creates docking sites for E3 ubiquitination ligases

Ubiquitine targets proteins for degradation

IkB and NFkB get activated by phosphorylation and release of regulatory subunit

Question 10

NFAT

Answer 10

Needs Calmodulin and Calcineurin for activation

Question 11

BCR and Co-Receptors

Answer 11

B cell receptor (BCR) consists of the Ag receptor w/ Igα and Igβ (these are signaling molecules)

B cell co-receptor:
-e.g. CD21, CD32, CD19 associate w/ BCR complex especially when they are linked with antigen-complement/antibody complex

LAT brings in ITAM region so it gets hyperphosphorylated..more and more activation of tyrosine kinase receptors

Question 12

Main membrane receptor

Answer 12

IgM

Igα and Igβ are different than TCRα and TCRβ. They have ITAMs in them which will bring in proteins

Question 13

Role of Complement in B cell activation

Answer 13

B cells have a CR2 complement that gets engaged by antigens. Starts a signaling cascade and this enhances B cell activation

Question 14

Inhibitory signals to turn off immune response

Answer 14

Phosphotases are recruited

Turning off by E3 ubiquitin ligases

Inhibitory receptors have: ITIM (not ITAM)

Question 15

FcγRIIB

Answer 15

Important attenuator of signaling in activated B cells, DCs and macrophages

Has ITIMs in it

Question 16

JAK STAT is downstream of cytokines

Answer 16

True

Question 17

Type 1 and type 2 cytokines go through what?

Answer 17

JAK STAT

Question 18

Type II Cytokine receptors

Answer 18

Also called Interferon Receptor Family

Question 19

TNF receptor signaling

Answer 19

Can result in NF-kB and MAP kinase activation or in the induction of apoptosis

Chemokines are only ones that use GPCR’s

Question 20

SARC is essential at cytoplasmic domains

Answer 20

True