Lecture 7 (part I)

Question 1

What initiates signal transduction?

Answer 1

Phosphorylation of Tyr/Ser/Thr in cytosolic portion of receptor by protein kinases

Question 2

Phosphatases in signal transduction

Answer 2

Modulatory function that usually inhibits signal transduction

Question 3

Modifications that facilitate signaling events

Answer 3

Ubiquitin addition, addition of lipids, acetylation/methylation

Question 4

Tyrosine kinase families

Answer 4

Src, Syk, Tec

Question 5

SH2 domains

Answer 5

Bind specific phosphotyrosine-containing polypeptides

Question 6

SH3 domains

Answer 6

Recognize proline-rich stretches in polypeptides

Question 7

PH domains

Answer 7

Recognize PIP3 or other phosphatidylinositol-derived lipids

Question 8

Adaptor proteins

Answer 8

Promote assembly of signaling molecule complexes; examples: LAT/BLNK; may contain SH2, SH3 domains

Question 9

Activating receptors

Answer 9

Contain ITAMs

Question 10

Inhibitory receptors

Answer 10

Contain ITIMs (such as Fc-gamma-RIIB)

Question 11

How many signaling chains and ITAMs does the TCR complex contain?

Answer 11

6 Signaling chains, 10 ITAMs

Question 12

Coreceptors

Answer 12

Transmembrane signaling proteins on lymphocyte that can facilitate Ag receptor activation by increasing ITAM phosphorylation

Question 13

Co-receptors on T cells

Answer 13

CD4, CD8

Question 14

Co-receptors on B cells

Answer 14

CR2/CD21 on B cells

Question 15

Inhibitory receptor of T cells

Answer 15

CTLA-4

Question 16

Inibitory receptors of B cells

Answer 16

CD22, Fc(gamma)RIIB

Question 17

Anergy

Answer 17

Unresponsiveness; reduced capacity to stimulate IL-2 in T cells