Nuclear Receptors

Question 1

Nuclear receptors are found?

Answer 1

inside the cell and are located both in the cytoplasm and the nucleus.

Question 2

Ligands for nuclear receptor are typically __________ which enter the cell by diffusion through the cell membrane.

Answer 2

Hormones

Question 3

When bound to hormones, nuclear receptors are able to bind ___________ ___________ in the nucleus .

Answer 3

Activator proteins.

Question 4

Nuclear receptors bound to activator proteins then bind to ___________________________ where they promote___________ of genes through activation of RNA polymerase.

Answer 4

Hormone response elements , transcription

Question 5

The net effect of activating nuclear proteins is increased synthesis of genes containing.

Answer 5

hormone response elements (HRE).

Question 6

It is important to remember that the effect of gene synthesis is dependent on the role the resulting proteins plays in the cell

True or false

Answer 6

True

For example, activating one gene may promote cell growth while another may promote cell cycle arrest or apoptosis.

Question 7

Some nuclear receptor ligands are involved in ______________ and _______________.

Answer 7

Cell growth and differentiation

Question 8

These nuclear receptor ligands include ____________ _____________.

Answer 8

Steroid hormones.

Question 9

Cell growth is regulated by controlling transcription of genes that promote cells to divide and/or differentiate.

True or false

Answer 9

True

Question 10

Other nuclear receptor ligands, such as ___________ and _____________ control cell metabolism by promoting transcription of genes that regulate metabolic activity.

Answer 10

Glucocorticoids and thyroid hormones.

Question 11

It is important to remember that the effect of a nuclear receptor is related to the __________ it activates and that there is a significant overlap between functions of different ___________________

Answer 11

Genes, hormone receptors

Example- glucocorticoids are involved in both regulate of metabolic activity and cell growth and cell death.

Question 12

The term Orphan receptors generally refers to?

Answer 12

receptors where no endogenous ligand has been identified.

Question 13

In the case of orphan nuclear receptor they do not appear to?

Answer 13

bind common hydrophobic molecules

Question 14

In regards to orphan nuclear receptors. They may be involved in ___________ regulation or in activating protective measures in cells.

Answer 14

Metabolic

Question 15

Their action is similar to other nuclear receptors except there is either_______________________________________.

Answer 15

no endogenous ligand or the ligand is unknown

Question 16

What is the zinc fingers(DNA binding domain) in a nuclear receptor.

Answer 16

​This region contains a “zinc finger” domain which is a specialized DNA binding structure in proteins that must access the base pairing in DNA in order to “read” the sequence

Question 17

the zinc finger region enables the protein to

Answer 17

bind to specific DNA sequences

Question 18

In nuclear receptors, there are two zinc finger domains linked by.

Answer 18

A hinge region

Question 19

Flexing of the hinge plays a role in positioning the zinc fingers so that the receptor can bind the _____

Answer 19

HRE

Question 20

The regulator domain is at the protein’s N-terminal end on the nuclear receptor and controls the activation of the________ and ______________.

Answer 20

receptor and its ability to bind and activate transcription

Question 21

Within this region is the _____ domain that permits a low level of activation of the receptor even in the absence of _____

Answer 21

AT-1, ligand

Question 22

The ligand binding domain binds _________, ____________ and ________ ________ of the receptors.

Answer 22

Agonists ,antagonists and inverse agonists

Question 23

In the ligand binding domain Binding of ________ activates the receptor and enables it to bind activator and DNA thus initiating transcription activation. ____________ can prevent this process.

Answer 23

Agonists, Antagonists

Question 24

Type 1 receptors are located outside the ________. They are bound to molecular chaperone proteins called ______________. On binding ligand, they dimerize and dissociate from the _____________. They then move into the nucleus where they bind _________ and ______ and activate transcription.

Answer 24

Nucleus, Heat Shock proteins, Heat shock proteins, heat shock proteins, activator and HREs

Question 25

Type 2 receptors are _______, bound to ____________ in the _______.

Answer 25

Diners, repressor proteins nucleus

Question 26

When ligands bind to type 2 receptor dimers, the _________ is released and a ____________ binds . This complex binds to the _______ and activates transcription. In the absence of ligand, the co-repressor prevents transcription.

Answer 26

Co-repressor, co-activator, HRE

Question 27

Type 3 receptors are similar to type 1 but differ in the structure of the ____ they bind to.

Answer 27

HREs

Question 28

Type 2 bind to inverted repeats or palindromic sequences while Type 1 receptors bind to direct repeats.
True or false

Answer 28

True

Question 29

The difference between an inverted repeat and direct repeat is that the repeated sequence in an inverted repeats is the reverse compliment while a direct repeat is exactly the same as the first sequence.

True or False

Answer 29

True

The repeats may be at a large distance from one another or close together.

Question 30

In regards to nuclear receptors.

Agonists: Activate the receptor and enable binding of ___________ proteins. Increase __________.

Answer 30

Co-activator, transcription

Question 31

In regards to nuclear receptors Antagonists: Binding prevents activation of the receptor by preventing ___________ binding.

Answer 31

Co- activator

Question 32

IN regards to nuclear receptors Inverse Agonists: Inverse agonists decrease the activity of a ________________when no agonist is bound. As mentioned in objective 5 above, the AT-1 region allows some activation of the receptor in the absence of the agonist. Inverse agonist block this activation

Answer 32

Nuclear receptor,