Steroid Hormones Receptors


Question H-02

 

 

Answer: (b)

 

Steroid and thyroid hormones are hydrophobic and diffuse from their binding proteins in the plasma, across the plasma membrane to intracellular localized receptors.

 

These receptors are proteins located in the cytosol and in the nucleus. They belong to the nuclear superfamily of receptors that include receptors for Vitamin A, Vitamin D and other hydrophobic metabolites. Receptors for steroid hormones (Type I receptors) are typically located in the cytosol, associated to Heat Shock Proteins (HSP).

 

When the hormone diffuse into the cytosol,  binds to these receptors, releasing the HSP, and  the resultant complex of steroid and receptor travels to the nucleus.

 

 In the nucleus, the Hormone-receptor complex recognize and bind to specific sequences of nucleotides in the DNA, called Hormone Response Elements (HRE).

 

This interaction Hormone-Receptor-HRE modify the expression of the associated gen, regulating the production of mRNA for specific proteins.

 

 

More information:

 

King, M.W.: The Medical Biochemistry page: Steroid Hormones and receptors

 

 

Kimball’s Biology Pages: Steroid Hormone Receptors

 

Steroid Hormones and receptors

 

 

Recommended videos availables in You Tube:

 

 

1.- A short video explaining the basic of the cellular mechanism of steroid hormones action:

 

 

 

2.- A very detailed lecture about the Nuclear receptors family:

 

 

 

 

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Q: Hormones, Receptors and Second Messengers


 

 

Question H-01

 

A typical characteristic of hormones that use the second messenger mechanism is that:

 

a)     they can not pass through the plasma membrane

b)     the receptor is located in the cytosol

c)      the receptor is located in the nucleus

d)     the receptor is not necessary

e)     the receptor binds to the hormone to allow it to enter the cell

 

 

      Answer to H-01

  

 

Question H-02

 

Receptors for steroid hormones can be found:

 

a)     in the plasma membrane

b)     in the cytosol

c)      in the mitochondria

d)     in the ribosomes

e)     in the Golgi apparatus

 

 Answer to H-02

 

 

Question H-03

 

The binding of insulin to the insulin receptor triggers:

 

a)     the interaction of the receptor with a protein G

b)     the activation of  adenyl ciclase

c)      the activation of phospholipase C

d)     a decrease of GLUT4 in the plasma membrane

e)     tyrosine kinase activity

   

      Answer to H-03

 

 

Question H-04

 

 

Which of the of the following hormones use cAMP as second messenger?

 

a)     Insulin

b)     Thyroxin

c)      Progesterone

d)     Aldosterone

e)     Glucagon

 

Answer to H-04

  

   

Question H-05

 

Hormones that act through Phospholipase C activation, in fact are using three second messengers:

 

 

a)     cAMP, Diacylglycerol and Ceramide

b)     cAMP, , Ca++ and Diacylglycerol

c)      cAMP , Ca++ and Inositol 1,4,5 triphosphate

d)     cAMP, Diacylglycerol and Inositol 1,4,5 triphosphate

e)     cAMP, Ca++ and ceramide

f)       Ca++, Diacylglycerol and ceramide

g)     Ca++, Diacylglycerol and Inositol 1.4.5 triphosphate

h)    Ca++, Ceramide, Inositol 3,4,5 triphosphate

i)       Ceramide, Diacylglycerol and Inositol 1,4,5 triphosphate.

 

  Answer to H-05