module 05 section 02 (cytokine receptors)

Question 1

cytokine receptors are divided into classes based on what?

Answer 1

their structural and functional differences

Question 2

what are the 5 cytokine receptor classes?

Answer 2

(1) Ig superfamily receptors
(2) class I cytokine receptors
(3) class II cytokine receptors
(4) TNF receptor family
(5) chemokine receptor family

Question 3

describe the Ig superfamily cytokine receptors

what is(are) their ligand(s)?

Answer 3

• has the same Ig domain structure that’s found in MHC and Igs
• ligand: IL-1

Question 4

what is the role of IL-1?

Answer 4

pro-inflammatory cytokine that plays an important role in inducing fever through stimualtion of the hypothalamus

Question 5

describe the class I cytokine receptors (aka hematopoietin receptor family)

what is(are) their ligand(s)?

Answer 5

• these have the Trp-Ser-X-Trp-Ser (WSXWS) amino acid motif

- ligands: IL-2, IL-3, pIL-4, IL-5, IL-6, IL-7, IL-12, IL-13

Question 6

what is the role of IL-2?

Answer 6

assists in the proliferation of CD4+ cells

Question 7

what is the role of pIL-4?

Answer 7

promotes the differentiation of activated T-cells into Th2 cells

Question 8

what is the role of IL-7?

Answer 8

required to drive proliferation and survival of pre B-cells from late pro B-cells in B-cell development

Question 9

describe class II cytokine receptors (aka interferon receptor family)

what is(are) their ligand(s)?

Answer 9

• similar in structure to class I but do not have the WSXWS motif
• characterized by the presence of cys disulfide bonds
• lingads: INF-a, INF-B, INF-y, IL-10

Question 10

describe the TNF receptor family

what is(are) their ligand(s)?

Answer 10

• these have cys-rich domains

- ligands: TNF-a, TNF-B, CD40L, FAS

Question 11

what is the role of CD40L?

Answer 11

protein primarily expressed on activated T-cells and has roles in B-cell growth, differentiation and isotype switching

Question 12

describe the chemokine receptor family

what is(are) their ligand(s)?

Answer 12

• belong to the G-protein coupled receptors
• contain 7 transmembrane domains
• also called heptahelical or serpentine receptors
  ligands: CCR5, CXCR4

Question 13

explain the role of CCR5 and CXCR4

Answer 13

important co-receptors for HIV

Question 14

what are 2 important structural features of cytokine receptors?

Answer 14

redundancy and pleiotropy

Question 15

describe redundancy in terms of cytokine receptors

Answer 15

• cytokine receptors are often composed of one or more chains
• different combinations of the chains for a given receptor will bind the same cytokine to induce cellular signals (with different affinities tho)

Question 16

describe pleiotropy in terms of cytokine receptors

Answer 16

• cytokine receptors may exhibit a common chain that allows the receptor to bind unique cytokines depending on their additional cytokine-specific subunit(s)
• e.g. many class I receptors (IL-2, IL-15, IL-7, IL-9 and IL-4) share a common signal transducing unit