Nuclear Receptors

Question 1

How many receptors make up the Nuclear Receptors

Answer 1

48

Question 2

How many domains do nuclear receptors have

Answer 2

3

Question 3

What is an orphan receptor

Answer 3

endogenous ligand has yet to be identified

Question 4

what is an endogenous ligand

Answer 4

endogenous ligand in regard to NRs describes a naturally occurring small molecule that elicits a conformational change in the NR upon binding

Question 5

What are the 2 class of function the nuclear receptor experience

Answer 5

Homodimer

Heterodimer

Question 6

What is a homodimer

Answer 6

protein composed of two polypeptide chains that are identical in the order, number, and kind of their amino acid residues.

Question 7

what is a heterodimer

Answer 7

a protein composed of two polypeptide chains differing in composition in the order, number, or kind of their amino acid residues

Question 8

What is another term for nuclear receptor

Answer 8

Ligand - Activated gene regulatory proteins

transcription factors

Question 9

Where can nuclear receptors be found

Answer 9

Cytosol or nucleus however they are not associated with the lipid membranes

Question 10

What are the 6 families of nuclear receptor

Answer 10

Thyroid receptor like

retinoid X receptor like

Oestrogen Receptor Like

Nerve growth Factor IB Like

Steroidogenic factor like

Germ Cell Nuclear Factor Like

Question 11

What is the structure of a nuclear receptor (general)

Answer 11

It has a C and N Termnal

The C terminal acts as a ligand binding domain

There is a DNA binding domain which is followed by the N terminal

The N terminal acts as the transcription activating domain

Question 12

Describe the Activators of nuclear receptors

Answer 12

they are small hydrophobic molecule that must be transported around the body in the blood stream

Question 13

What is the purpose of the binding of a carrier protein to the nuclear receptor

Answer 13

Specific carrier proteins bind to increase solubility

Dissociation then occurs before entering the cell

Question 14

Describe the process by which binding proteins are delivered to the target tissue from the thyroid

Answer 14

The Thyroid secretes the activator (Hormone) which is delivered to its target via the blood stream. Where it then dissociates to its target.

Question 15

Describe the mechanism of action by which a nuclear receptor is affected.

Answer 15

Agonists are typically hydrophobic and hence can freely diffuse across the plasma membrane.

Agonists then bind to the ligand binding domain acting as a molecular switch

A conformational change occurs upon binding within the receptor

The receptors then dimerize and translocate to the nucleus

Question 16

What are glucocorticoid receptors involved in

Answer 16

Upregulation of anti-inflammatory proteins such as the lipcortins

Question 17

what is the purpose of lipocortins

Answer 17

suppress the activity of phospholipase A2

Question 18

What does phospholipase contribute too

Answer 18

It contributes to inflammation by producing the intermediate for arachidonic acid

Question 19

What is dexamethasone used for

Answer 19

dexamethasone has anti inflammatory and immunosuppressant effects

It can be used to treat:

Rheumatic diseases
Skin Diseases
severe allergic reactions

Question 20

What are oestrogen receptors regulators off

Answer 20

they are key regulators of cell growth and differentiation

Question 21

what are the two oestrogen receptors that affect biological effects

Answer 21

ER ALPHA

ER BETA

Question 22

What is tamoxifen

Answer 22

acts as oestrogen receptor antagonist in breast tissues

it also acts as oestrogen receptors in other tissues

it is commonly known as a selective oestrogen receptor molecule

Question 23

What determines whether tamoxifen is an agonist or antagonist

Answer 23

the ratio of co activator to co repressor proteins in tissues

Question 24

what must tamoxifen be metabolized by

Answer 24

Cytochromes to produce 4-hydroxytamoxifen, N-desmethyl-4hydroytamofien and endoxifen