Sandbox Reserved 489: Difference between revisions

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Renin is secreted by the kidneys. The kidneys act both directly and indirectly to regulate arterial blood pressure and provide the major long term mechanism of blood pressure and control. The direct mechanism changes blood volume independently of hormones. When blood pressure and blood volume increase the kidneys can not filter all of the liquids and thus liquids are lost in the urine to decrease blood pressure and blood volume.

The indirect mechanism, or the [http://en.wikipedia.org/wiki/Renin-angiotensin_system renin-angiotensin system] (RAS), controls blood volume and blood pressure through renin and two forms of [http://en.wikipedia.org/wiki/Angiotensin angiotensin]. Renin is involved in the first step of a cascade that eventually produces angiotensin II. The specialized granular cells of the [http://en.wikipedia.org/wiki/Juxtaglomerular_apparatus juxtaglomerular apparatus] secrete renin when stimulated by the [http://en.wikipedia.org/wiki/Macula_densa macula densa] when blood pressure or blood volume decreases. Renin circulating in the blood stream cleaves a small 10 residue portion of plasma protein angiotensinogen that is secreted by the liver. Cleavage of angiotensinogen produces the inactive precursor angiotensin I that is converted to angiotensin II by [http://en.wikipedia.org/wiki/Angiotensin-converting_enzyme angiotensin-converting enzyme] primarily in the lungs. Angiotensin II increases blood pressure in three ways.

The indirect mechanism, or the [http://en.wikipedia.org/wiki/Renin-angiotensin_system renin-angiotensin system] (RAS), controls blood volume and blood pressure through renin and two forms of [http://en.wikipedia.org/wiki/Angiotensin angiotensin]. Renin is involved in the rate limiting first step of a cascade that eventually produces angiotensin II. The specialized granular cells of the [http://en.wikipedia.org/wiki/Juxtaglomerular_apparatus juxtaglomerular apparatus] secrete renin when stimulated by the [http://en.wikipedia.org/wiki/Macula_densa macula densa] when blood pressure or blood volume decreases. Renin circulating in the blood stream cleaves a small 10 residue portion of plasma protein angiotensinogen that is secreted by the liver. Cleavage of angiotensinogen produces the inactive precursor angiotensin I that is converted to angiotensin II by [http://en.wikipedia.org/wiki/Angiotensin-converting_enzyme angiotensin-converting enzyme] primarily in the lungs. Angiotensin II increases blood pressure in three ways.

:*Angiotensin II constricts blood vessels by influencing smooth muscle tissue. The heart pumps faster to overcome the constricted arteries and blood pressure rises.

:*Angiotensin II stimulates the [http://en.wikipedia.org/wiki/Adrenal_cortex adrenal cortex] to secrete [http://en.wikipedia.org/wiki/Aldosterone aldosterone] that causes renal adsorption of sodium. when sodium moves into the blood stream water follows to increase the blood volume.

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==Structure==

~~----~~

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==Function==

~~----~~

Renin secretion is stimulated by a decrease in arterial blood pressure, a decrease in sodium chloride levels in kidney [http://en.wikipedia.org/wiki/Nephron nephrons], or [http://en.wikipedia.org/wiki/Sympathetic_nervous_system sympathetic nervous system] activity.

The substrate of renin, angiotensinogen, is a 452 amino acid residue in humans. Renin utilizes two aspartate residues in the <scene name='Sandbox_Reserved_489/Activesiteasps2/2'>active site</scene> to cleave the peptide bond between leucine and valine residues on angiotensinogen. Angiotensin I is an inactive short peptide of 10 amino acids that is produced by the renin cleavage reaction. The two aspartate residues operate most efficiently at acidic pH because one of the carbonyl groups must be deprotonated to accept a proton from water. The mechanism of the catalysis is an acid base transfer of water between the two aspartate residues. Initially one aspartate residue carbonyl is deprotonated and the other is protonated. The deprotonated aspartate removes a proton from water allowing the water to attack the carbonyl of the beptide bond in the substrate forming a tetrahedral oxyanion intermediate on the substrate. Rearrangement of the intermediate causes protonation of the amide on the substrate completing the cleavage reaction.

Renin can also bind the renin receptor [http://en.wikipedia.org/wiki/ATP6AP2 ATPase H(+)-transporting lysosomal accessory protein 2] (ATP6AP2) to convert angiotensinogen to angiotensin I at a much greater rate.

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@@ Line 10: / Line 10: @@
 Renin is secreted by the kidneys.  The kidneys act both directly and indirectly to regulate arterial blood pressure and provide the major long term mechanism of blood pressure and control.  The direct mechanism changes blood volume independently of hormones.  When blood pressure and blood volume increase the kidneys can not filter all of the liquids and thus liquids are lost in the urine to decrease blood pressure and blood volume.
-The indirect mechanism, or the [http://en.wikipedia.org/wiki/Renin-angiotensin_system renin-angiotensin system]  (RAS), controls blood volume and blood pressure through renin and two forms of [http://en.wikipedia.org/wiki/Angiotensin angiotensin].  Renin is involved in the first step of a cascade that eventually produces angiotensin II.  The specialized granular cells of the [http://en.wikipedia.org/wiki/Juxtaglomerular_apparatus juxtaglomerular apparatus] secrete renin when stimulated by the [http://en.wikipedia.org/wiki/Macula_densa macula densa] when blood pressure or blood volume decreases.  Renin circulating in the blood stream cleaves a small 10 residue portion of plasma protein angiotensinogen that is secreted by the liver.  Cleavage of angiotensinogen produces the inactive precursor angiotensin I that is converted to angiotensin II by [http://en.wikipedia.org/wiki/Angiotensin-converting_enzyme angiotensin-converting enzyme] primarily in the lungs.  Angiotensin II increases blood pressure in three ways.
+The indirect mechanism, or the [http://en.wikipedia.org/wiki/Renin-angiotensin_system renin-angiotensin system]  (RAS), controls blood volume and blood pressure through renin and two forms of [http://en.wikipedia.org/wiki/Angiotensin angiotensin].  Renin is involved in the rate limiting first step of a cascade that eventually produces angiotensin II.  The specialized granular cells of the [http://en.wikipedia.org/wiki/Juxtaglomerular_apparatus juxtaglomerular apparatus] secrete renin when stimulated by the [http://en.wikipedia.org/wiki/Macula_densa macula densa] when blood pressure or blood volume decreases.  Renin circulating in the blood stream cleaves a small 10 residue portion of plasma protein angiotensinogen that is secreted by the liver.  Cleavage of angiotensinogen produces the inactive precursor angiotensin I that is converted to angiotensin II by [http://en.wikipedia.org/wiki/Angiotensin-converting_enzyme angiotensin-converting enzyme] primarily in the lungs.  Angiotensin II increases blood pressure in three ways.
 :*Angiotensin II constricts blood vessels by influencing smooth muscle tissue. The heart pumps faster to overcome the constricted arteries and blood pressure rises.
 :*Angiotensin II  stimulates the [http://en.wikipedia.org/wiki/Adrenal_cortex adrenal cortex] to secrete [http://en.wikipedia.org/wiki/Aldosterone aldosterone] that causes renal adsorption of sodium.  when sodium moves into the blood stream water follows to increase the blood volume.
@@ Line 23: / Line 23: @@
 ==Structure==
-----
 <Structure load='2ren' size='400' frame='true' align='right' caption='Mature Renin' scene='Insert optional scene name here' />
@@ Line 31: / Line 30: @@
 ==Function==
-----
 Renin secretion is stimulated by a decrease in arterial blood pressure, a decrease in sodium chloride levels in kidney [http://en.wikipedia.org/wiki/Nephron nephrons], or [http://en.wikipedia.org/wiki/Sympathetic_nervous_system sympathetic nervous system] activity.
+The substrate of renin, angiotensinogen, is a 452 amino acid residue in humans.  Renin utilizes two aspartate residues in the <scene name='Sandbox_Reserved_489/Activesiteasps2/2'>active site</scene> to cleave the peptide bond between leucine and valine residues on angiotensinogen.  Angiotensin I is an inactive short peptide of 10 amino acids that is produced by the renin cleavage reaction.  The two aspartate residues operate most efficiently at acidic pH because one of the carbonyl groups must be deprotonated to accept a proton from water.  The mechanism of the catalysis is an acid base transfer of water between the two aspartate residues.  Initially one aspartate residue carbonyl is deprotonated and the other is protonated.  The deprotonated aspartate removes a proton from water allowing the water to attack the carbonyl of the beptide bond in the substrate forming a tetrahedral oxyanion intermediate on the substrate.  Rearrangement of the intermediate causes protonation of the amide on the substrate completing the cleavage reaction.
+Renin can also bind the renin receptor [http://en.wikipedia.org/wiki/ATP6AP2 ATPase H(+)-transporting lysosomal accessory protein 2] (ATP6AP2) to convert angiotensinogen to angiotensin I at a much greater rate.