Alpha crystallin: Difference between revisions

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Along with the contents and structure of the lens itself, the alpha-crystallin maintains the eye's clarity by acting as chaperone-like proteins in order to prevent aberrant, or standard deviating, protein interactions. The chaperone capabilities of these proteins also allow the prevention of non-native proteins becoming insoluble under stressful conditions like chemical reductions, oxidations, or elevation of temperatures. The combined abilities of the chaperone-like alpha-crystallin means that they can aid in the prevention of the formation of large, dense, light scattering masses. For example, one of the effects of old age is cataract formation, and alpha-crystallin is the known culprit for this development. As alpha-crystallin is depleted within the eye, its defensive efforts go with it, which allows these masses to take form. The alpha-crystallin within the eye is the primary protectant against the age-induced deterioration of the lens. It allows the effects of aging to be reduced for significant periods of time.

Alpha-crystallin is also known to inhibit apoptosis from occurring, enhance the resistance of stress on cells, and protect the cytoskeleton. Clearly, this protein has many vital functions in the body, but primarily in the eye. Having a high alpha-crystallin index, or the amount of alpha-crystallin present in the space is crucial for proper eye health and maintenance.

~~== Evolutionary Development ==~~

Alpha crystallin is a product of evolutionary development as the protein was derived from a family of heat shock proteins (HSP) called small heat shock proteins (sHSP). Heat shock proteins are specialized proteins that are made when a cell is exposed to high temperatures, and it is present in all plants and animals. In a series of gene duplication and divergences, the initially small family of heat shock proteins was able to adapt and gain a new novel function. The component alpha-crystallin was also formed by gene recruitment which is the co-option of a particular gene for a different function as a result of mutation. This form of recruitment took place in the previously existing heat shock proteins. It allowed the newly formed alpha-crystallin to take on the characteristics and functions of the pre-existing proteins. For example, the small heat shock proteins were able to cradle other cells when enduring intense stress in order to prevent them from distorting their shape, which is a current function that the alpha-crystallin acts on in the eye's lens. This is known to be true from a series of crystallin genes found in the specific family of small heat shock proteins. This set of crystallin genes also included regulatory elements that allow gene expression to be found in stressed cells and lenses. After several mutation events to the regulatory region, the production of heat-shock genes, a precursor to crystallin, was able to develop on the surface of the eye. After years of evolution, it transformed into the crystallin components and subunits we know today.

Uniquely, the family of heat shock proteins from which the alpha-crystallin was derived and the alpha-crystallin in the eye today contain a core called the alpha-crystallin domain (ADC). This core can be found in the monomers of today's crystallin proteins and gives us conclusive evidence of the protein's evolutionary advancements. This center, or core, is approximately 90 amino acids long and has ends with variable hydrophobic N-terminal domains as well as variable hydrophilic C-terminal extensions. The alpha-crystallin domain is key to the formation of dimers which is the primary building block of oligomers. The N-terminal domain of the alpha-crystallin is not necessary for the protein to function as a chaperone, nor does it contribute to dimerization. It does, however, appear to be required for the formation of high-order aggregates. The C-terminal extensions consist of about 25 residues that are crucial to alpha-crystallin as they are the primary contributors in its ability to act as a chaperone-like protein. The C-terminal also contains the IXI/V motif, which includes two isoleucine residues that are separated with an intervening residue. The IXI motif is able to promote chaperone action because it stimulates intersubunit interactions and provides chaperone site accessibility. Alpha crystallin also prevents denatured proteins from solidifying, which helps to retain the eye's transparency and prevent the formation of cataracts. It is also known to increase the cellular tolerance to stress. These features are very similar to the small heat shock proteins that range from 15 to 30 kDa, particularly in their C-terminal halves.

== Structural highlights ==

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Alpha-A crystallin is made of 173 amino acids arranged in <scene name='88/881544/Beta_sheet/1'>a beta sheet pattern</scene>. The molecular mass of the alpha-A subunit is 19.8 kDa, and the homooligomer weighs 660 kDa. On the other hand, Alpha-B crystallin has 165 amino acids arranged in seven beta-sheets, has a molecular mass of 20 kDa, and its homooligomer weight is 620 kDa. Together, the alpha-crystallin protein has <scene name='88/881544/Zinc_and_zinc_binding_sites/3'>four Zinc binding sites</scene>, all of which are in the same position as the four metal-binding sites. Within the crystallin is two tryptophan residues, Trp9 and Trp60, both of which can be found in the alpha-B crystallin subunit.

== Evolutionary Development ==

Alpha crystallin is a product of evolutionary development as the protein was derived from a family of heat shock proteins (HSP) called small heat shock proteins (sHSP). Heat shock proteins are specialized proteins that are made when a cell is exposed to high temperatures, and it is present in all plants and animals. In a series of gene duplication and divergences, the initially small family of heat shock proteins was able to adapt and gain a new novel function. The component alpha-crystallin was also formed by gene recruitment which is the co-option of a particular gene for a different function as a result of mutation. This form of recruitment took place in the previously existing heat shock proteins. It allowed the newly formed alpha-crystallin to take on the characteristics and functions of the pre-existing proteins. For example, the small heat shock proteins were able to cradle other cells when enduring intense stress in order to prevent them from distorting their shape, which is a current function that the alpha-crystallin acts on in the eye's lens. This is known to be true from a series of crystallin genes found in the specific family of small heat shock proteins. This set of crystallin genes also included regulatory elements that allow gene expression to be found in stressed cells and lenses. After several mutation events to the regulatory region, the production of heat-shock genes, a precursor to crystallin, was able to develop on the surface of the eye. After years of evolution, it transformed into the crystallin components and subunits we know today.

Uniquely, the family of heat shock proteins from which the alpha-crystallin was derived and the alpha-crystallin in the eye today contain a core called the alpha-crystallin domain (ADC). This core can be found in the monomers of today's crystallin proteins and gives us conclusive evidence of the protein's evolutionary advancements. This center, or core, is approximately 90 amino acids long and has ends with variable hydrophobic N-terminal domains as well as variable hydrophilic C-terminal extensions. The alpha-crystallin domain is key to the formation of dimers which is the primary building block of oligomers. The N-terminal domain of the alpha-crystallin is not necessary for the protein to function as a chaperone, nor does it contribute to dimerization. It does, however, appear to be required for the formation of high-order aggregates. The C-terminal extensions consist of about 25 residues that are crucial to alpha-crystallin as they are the primary contributors in its ability to act as a chaperone-like protein. The C-terminal also contains the IXI/V motif, which includes two isoleucine residues that are separated with an intervening residue. The IXI motif is able to promote chaperone action because it stimulates intersubunit interactions and provides chaperone site accessibility. Alpha crystallin also prevents denatured proteins from solidifying, which helps to retain the eye's transparency and prevent the formation of cataracts. It is also known to increase the cellular tolerance to stress. These features are very similar to the small heat shock proteins that range from 15 to 30 kDa, particularly in their C-terminal halves.

~~</StructureSection>~~

== References ==

Alpha crystallin: Difference between revisions

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@@ Line 6: / Line 6: @@
 Along with the contents and structure of the lens itself, the alpha-crystallin maintains the eye's clarity by acting as chaperone-like proteins in order to prevent aberrant, or standard deviating, protein interactions. The chaperone capabilities of these proteins also allow the prevention of non-native proteins becoming insoluble under stressful conditions like chemical reductions, oxidations, or elevation of temperatures. The combined abilities of the chaperone-like alpha-crystallin means that they can aid in the prevention of the formation of large, dense, light scattering masses. For example, one of the effects of old age is cataract formation, and alpha-crystallin is the known culprit for this development. As alpha-crystallin is depleted within the eye, its defensive efforts go with it, which allows these masses to take form. The alpha-crystallin within the eye is the primary protectant against the age-induced deterioration of the lens. It allows the effects of aging to be reduced for significant periods of time.
 Alpha-crystallin is also known to inhibit apoptosis from occurring, enhance the resistance of stress on cells, and protect the cytoskeleton. Clearly, this protein has many vital functions in the body, but primarily in the eye. Having a high alpha-crystallin index, or the amount of alpha-crystallin present in the space is crucial for proper eye health and maintenance.
-== Evolutionary Development ==
-Alpha crystallin is a product of evolutionary development as the protein was derived from a family of heat shock proteins (HSP) called small heat shock proteins (sHSP). Heat shock proteins are specialized proteins that are made when a cell is exposed to high temperatures, and it is present in all plants and animals. In a series of gene duplication and divergences, the initially small family of heat shock proteins was able to adapt and gain a new novel function. The component alpha-crystallin was also formed by gene recruitment which is the co-option of a particular gene for a different function as a result of mutation. This form of recruitment took place in the previously existing heat shock proteins. It allowed the newly formed alpha-crystallin to take on the characteristics and functions of the pre-existing proteins. For example, the small heat shock proteins were able to cradle other cells when enduring intense stress in order to prevent them from distorting their shape, which is a current function that the alpha-crystallin acts on in the eye's lens. This is known to be true from a series of crystallin genes found in the specific family of small heat shock proteins. This set of crystallin genes also included regulatory elements that allow gene expression to be found in stressed cells and lenses. After several mutation events to the regulatory region, the production of heat-shock genes, a precursor to crystallin, was able to develop on the surface of the eye. After years of evolution, it transformed into the crystallin components and subunits we know today.
-	Uniquely, the family of heat shock proteins from which the alpha-crystallin was derived and the alpha-crystallin in the eye today contain a core called the alpha-crystallin domain (ADC). This core can be found in the monomers of today's crystallin proteins and gives us conclusive evidence of the protein's evolutionary advancements. This center, or core, is approximately 90 amino acids long and has ends with variable hydrophobic N-terminal domains as well as variable hydrophilic C-terminal extensions. The alpha-crystallin domain is key to the formation of dimers which is the primary building block of oligomers. The N-terminal domain of the alpha-crystallin is not necessary for the protein to function as a chaperone, nor does it contribute to dimerization. It does, however, appear to be required for the formation of high-order aggregates.  The C-terminal extensions consist of about 25 residues that are crucial to alpha-crystallin as they are the primary contributors in its ability to act as a chaperone-like protein. The C-terminal also contains the IXI/V motif, which includes two isoleucine residues that are separated with an intervening residue. The IXI motif is able to promote chaperone action because it stimulates intersubunit interactions and provides chaperone site accessibility. Alpha crystallin also prevents denatured proteins from solidifying, which helps to retain the eye's transparency and prevent the formation of cataracts. It is also known to increase the cellular tolerance to stress. These features are very similar to the small heat shock proteins that range from 15 to 30 kDa, particularly in their C-terminal halves.
 == Structural highlights ==
@@ Line 20: / Line 15: @@
 Alpha-A crystallin is made of 173 amino acids arranged in <scene name='88/881544/Beta_sheet/1'>a beta sheet pattern</scene>. The molecular mass of the alpha-A subunit is 19.8 kDa, and the homooligomer weighs 660 kDa. On the other hand, Alpha-B crystallin has 165 amino acids arranged in seven beta-sheets, has a molecular mass of 20 kDa, and its homooligomer weight is 620 kDa. Together, the alpha-crystallin protein has <scene name='88/881544/Zinc_and_zinc_binding_sites/3'>four Zinc binding sites</scene>, all of which are in the same position as the four metal-binding sites. Within the crystallin is two tryptophan residues, Trp9 and Trp60, both of which can be found in the alpha-B crystallin subunit.
+== Evolutionary Development ==
+Alpha crystallin is a product of evolutionary development as the protein was derived from a family of heat shock proteins (HSP) called small heat shock proteins (sHSP). Heat shock proteins are specialized proteins that are made when a cell is exposed to high temperatures, and it is present in all plants and animals. In a series of gene duplication and divergences, the initially small family of heat shock proteins was able to adapt and gain a new novel function. The component alpha-crystallin was also formed by gene recruitment which is the co-option of a particular gene for a different function as a result of mutation. This form of recruitment took place in the previously existing heat shock proteins. It allowed the newly formed alpha-crystallin to take on the characteristics and functions of the pre-existing proteins. For example, the small heat shock proteins were able to cradle other cells when enduring intense stress in order to prevent them from distorting their shape, which is a current function that the alpha-crystallin acts on in the eye's lens. This is known to be true from a series of crystallin genes found in the specific family of small heat shock proteins. This set of crystallin genes also included regulatory elements that allow gene expression to be found in stressed cells and lenses. After several mutation events to the regulatory region, the production of heat-shock genes, a precursor to crystallin, was able to develop on the surface of the eye. After years of evolution, it transformed into the crystallin components and subunits we know today.
+	Uniquely, the family of heat shock proteins from which the alpha-crystallin was derived and the alpha-crystallin in the eye today contain a core called the alpha-crystallin domain (ADC). This core can be found in the monomers of today's crystallin proteins and gives us conclusive evidence of the protein's evolutionary advancements. This center, or core, is approximately 90 amino acids long and has ends with variable hydrophobic N-terminal domains as well as variable hydrophilic C-terminal extensions. The alpha-crystallin domain is key to the formation of dimers which is the primary building block of oligomers. The N-terminal domain of the alpha-crystallin is not necessary for the protein to function as a chaperone, nor does it contribute to dimerization. It does, however, appear to be required for the formation of high-order aggregates.  The C-terminal extensions consist of about 25 residues that are crucial to alpha-crystallin as they are the primary contributors in its ability to act as a chaperone-like protein. The C-terminal also contains the IXI/V motif, which includes two isoleucine residues that are separated with an intervening residue. The IXI motif is able to promote chaperone action because it stimulates intersubunit interactions and provides chaperone site accessibility. Alpha crystallin also prevents denatured proteins from solidifying, which helps to retain the eye's transparency and prevent the formation of cataracts. It is also known to increase the cellular tolerance to stress. These features are very similar to the small heat shock proteins that range from 15 to 30 kDa, particularly in their C-terminal halves.
-</StructureSection>
 == References ==
 <references/>