User:Max Lein/Sandbox - Revision history

Max Lein at 12:46, 2 December 2008

2008-12-02T12:46:26Z

←Older revision		Revision as of 12:46, 2 December 2008
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-	{{Seed}}
	[[Image:1gpa.png\|left\|200px]]		[[Image:1gpa.png\|left\|200px]]

Max Lein at 10:16, 2 December 2008

2008-12-02T10:16:16Z

←Older revision		Revision as of 10:16, 2 December 2008
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	5. Glycogen storage site.		5. Glycogen storage site.

-	There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with R69 and R45' (prime denotes a residue from the adjacent subunit). The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.	+	There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues (Asp109, Glu110, Glu120, Glu501, Glu505 and Glu509) in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with R69 and R45' (prime denotes a residue from the adjacent subunit). In summary, the conformatino change causes an ordering of the N-terminal chain and a disordering of residues at the C-terminal. Once disordered, the C-terminal residues are no longer able to block substrate entry into the active site. The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.

	In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'T' state for low substrate affinity), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'R' state for high substrate affinity).		In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'T' state for low substrate affinity), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'R' state for high substrate affinity).
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	A New Allosteric site in Glycogen Phoshporylase b as a Target for Drug Interactions., Barford D, Hu SH, Johnson LN Structure. 2000. Vol. 8, No. 6, pp. 575-584.		A New Allosteric site in Glycogen Phoshporylase b as a Target for Drug Interactions., Barford D, Hu SH, Johnson LN Structure. 2000. Vol. 8, No. 6, pp. 575-584.
		+
		+	Electrostatic Effects in the Control of Glycogen Phosphorylase by Phosphorylation., Barford D., Johnson LN. Prot. Sci. 1994. Vol. 8, pp. 1726-1730.
	[[Category: Glycogen Phosphorylase]]		[[Category: Glycogen Phosphorylase]]
	[[Category: Oryctolagus cuniculus]]		[[Category: Oryctolagus cuniculus]]

Max Lein at 09:22, 2 December 2008

2008-12-02T09:22:08Z

←Older revision		Revision as of 09:22, 2 December 2008
Line 35:		Line 35:
	5. Glycogen storage site.		5. Glycogen storage site.

-	There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with ~~several arginine side chains~~. The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.	+	There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with R69 and R45' (prime denotes a residue from the adjacent subunit). The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.

-	In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'R' state), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'T' state).	+	In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'T' state for low substrate affinity), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'R' state for high substrate affinity).

	==Links==		==Links==

Max Lein at 09:02, 2 December 2008

2008-12-02T09:02:54Z

←Older revision		Revision as of 09:02, 2 December 2008
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	==About this Structure==		==About this Structure==
-	The PDB 1gpa contains 4 chains of the 'A' form of glycogen phosphorylase. Each subunit contains a phosphate group bound to Ser14, sulfate groups bound to two effector sites (sulfate acts as a mimic of phosphate groups), and the cofactor pyridoxal-5'-phosphate bound to K681.	+	The PDB 1gpa contains 4 chains of the 'A' form of glycogen phosphorylase. Each subunit contains a phosphate group bound to Ser14, sulfate groups bound to two effector sites (sulfate acts as a mimic of phosphate groups), and the cofactor pyridoxal-5'-phosphate bound to K681. See the links section at the end of this page for links to more structural information on glycogen phosphorylase.

	==Reaction==		==Reaction==
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	In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'R' state), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'T' state).		In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'R' state), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'T' state).

		+	==Links==

	1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].		1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].

Max Lein at 09:00, 2 December 2008

2008-12-02T09:00:26Z

←Older revision		Revision as of 09:00, 2 December 2008
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	==About this Structure==		==About this Structure==
		+	The PDB 1gpa contains 4 chains of the 'A' form of glycogen phosphorylase. Each subunit contains a phosphate group bound to Ser14, sulfate groups bound to two effector sites (sulfate acts as a mimic of phosphate groups), and the cofactor pyridoxal-5'-phosphate bound to K681.

	==Reaction==		==Reaction==

Max Lein at 08:56, 2 December 2008

2008-12-02T08:56:43Z

←Older revision		Revision as of 08:56, 2 December 2008
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	-->		-->
	{{STRUCTURE_1gpa\| PDB=1gpa \| SCENE= }}		{{STRUCTURE_1gpa\| PDB=1gpa \| SCENE= }}
-
-	===STRUCTURAL MECHANISM FOR GLYCOGEN PHOSPHORYLASE CONTROL BY PHOSPHORYLATION AND AMP===
-
-

	==About this Structure==		==About this Structure==

Max Lein at 08:33, 2 December 2008

2008-12-02T08:33:16Z

←Older revision		Revision as of 08:33, 2 December 2008
Line 45:		Line 45:
	1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].		1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].

-	==~~Reference~~==	+	==References==
	Structural mechanism for glycogen phosphorylase control by phosphorylation and AMP., Barford D, Hu SH, Johnson LN, J Mol Biol. 1991 Mar 5;218(1):233-60. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/1900534 1900534]		Structural mechanism for glycogen phosphorylase control by phosphorylation and AMP., Barford D, Hu SH, Johnson LN, J Mol Biol. 1991 Mar 5;218(1):233-60. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/1900534 1900534]
		+
		+	A New Allosteric site in Glycogen Phoshporylase b as a Target for Drug Interactions., Barford D, Hu SH, Johnson LN Structure. 2000. Vol. 8, No. 6, pp. 575-584.
	[[Category: Glycogen Phosphorylase]]		[[Category: Glycogen Phosphorylase]]
	[[Category: Oryctolagus cuniculus]]		[[Category: Oryctolagus cuniculus]]

Max Lein at 08:27, 2 December 2008

2008-12-02T08:27:11Z

←Older revision		Revision as of 08:27, 2 December 2008
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	==Reaction==		==Reaction==
-	Glycogen phosphorylase catalyzes the degradation of glycogen into glucose-1'-phosphate.	+	Glycogen phosphorylase (GP) catalyzes the degradation of the reducing end of glycogen into glucose-1-phosphate. It employs a cofactor called pyridoxal-5’ –phosphate, that is located in the active site and bound to a K681 residue with a Schiff base linkage. PLP shuttles the phosphate group onto the substrate.

	==History==		==History==
		+	This protein comes from the muscle tissue of [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. There is an isozyme from liver tissue that is regulated by glucagon instead of epinephrine, with a different gene that encodes it and different regulation properties.
		+
	Glycogen phosphorylase was the first phosphorylase enzyme to be discovered, and the first example of regulation via covalent modification.		Glycogen phosphorylase was the first phosphorylase enzyme to be discovered, and the first example of regulation via covalent modification.

Line 26:		Line 28:
	Subsequently, Earl Sutherland found that the 'B' form predominates in resting muscle and epinephrine triggers activation to form 'A'. Since then, many groups have worked on this enzyme, both to understand its mechanism and to discover drug targets. Crystal structures have been obtained for the protein in the 'A' and 'B' form, in the presence of natural substrates, inhibitors, and transition state analogs. Please see the end of this article for links to crystallographic information.		Subsequently, Earl Sutherland found that the 'B' form predominates in resting muscle and epinephrine triggers activation to form 'A'. Since then, many groups have worked on this enzyme, both to understand its mechanism and to discover drug targets. Crystal structures have been obtained for the protein in the 'A' and 'B' form, in the presence of natural substrates, inhibitors, and transition state analogs. Please see the end of this article for links to crystallographic information.

-	==~~Facts about~~ GP==	+	==Activity and Regulation of GP==
-	~~Protein comes from rabbit muscle tissue~~, ~~where energy from glucose~~ is ~~needed~~. ~~There is an isozyme from liver tissue~~ that ~~is regulated by glucagon instead of epinephrine, with a different gene that encodes it and different regulation properties~~.	+	In its active form, GP is a dimer of two identical subunits. The subunits make interactions that stabilize the final structure.
-	~~Activity and Regulation of GP~~	+
-	1. ~~GP catalyzes the clipping of a glucose molecule off of the reducing end of glycogen~~. ~~It employs a cofactor called pyridoxal~~-~~5’ –phosphate~~, ~~that is located in the active~~ site and ~~bound to a lysine residue with a Schiff base linkage. PLP shuttles the phosphate group onto the substrate~~.	+	Each Sub-unit contains 5 potential effector sites:
-	2. There are two forms, A and B, ~~and two states, T and R, for the enzyme~~.	+	1. Ser14 phosphate-recognition site.
-	B ~~= nearly inactive dimer, stabilized~~ by ~~electrostatics at N-terminus (w/basic residues) interacting with pocket of acidic residues.~~	+	2. AMP activation / Glc-6-P inhibition site.
-	~~Phosphorylase~~ kinase catalyzes addition of phosphate to Ser14~~, tightens structure of~~ N-~~terminal portion of each chain, resulting in conformation change to form A~~.	+	3. Catalytic site that binds glycogen, Glc-1-P
-	~~Phosphorylation causes electrostatic interference between phosphate group and acidic residues, forcing~~ the ~~N-terminal domain out of the acidic environment and into~~ a ~~region with several arginine side chains.~~	+	4. Inhibitor site, 12Å from catalytic site, binds caffeine and related compounds.
-	~~Phosphatase removes phosphate, returns GP to form B.~~	+	5. Glycogen storage site.
-	~~Response~~ to hormone epinephrine ~~(in muscle)~~, (fight-or-flight response~~) or glucagon (~~in ~~liver), increases~~ available energy to organism as a whole.	+
-	- ~~In b form~~, ~~enzyme can be activated:~~	+	There are two forms of the enzyme, designated as 'A' and 'B', that are controlled hormonally. The 'B' form is converted into the 'A' form by phosphorylase kinase, which catalyzes the addition of phosphate from ATP to Ser14 near the N-terminus. This represents the final step in a signal transduction cascade in response to the hormone epinephrine, associated with the 'fight-or-flight' response and causing an increase in available energy to the organism as a whole. The N-terminus contains a high percentage of basic residues, which interact favorably with a pocket of acidic residues in the 'B' form. Once Ser14 is phosphorylated, the N-terminus is forced ~50Å away from the acidic residues, settling into a region with several arginine side chains. The enzyme phosphatase is able to remove the phosphate and return GP to form 'B'.
-	~~Activated by AMP, (cell doesn’t get signal, but needs energy for itself)~~.	+
-	~~Inactivated by ATP, glucose (cell already has enough energy for itself~~, ~~phosphorylation will not activate)~~	+
-	- ~~Having two overlaid levels of control allows~~ the ~~appropriate response in either situation~~.	+
-	~~- Phosphoglucomutase shifts carbon chain over 1~~.	+

		+	In addition, the 'A' and 'B' forms can be regulated futher by small molecules in the cell. This allows individual cells to ignore the hormonal signal if they already have enough available energy (at high concentrations of glucose derivatives or ATP, designated as the 'R' state), or activate GP without a hormonal signal when energy for the individual cell is needed (high concentrations of AMP, designated as the 'T' state).
		+

	1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].		1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].

Max Lein at 07:36, 2 December 2008

2008-12-02T07:36:35Z

←Older revision		Revision as of 07:36, 2 December 2008
Line 24:		Line 24:
	In the 1930s, the first work done by Carl and Gerty Cori. They proved that the enzyme exists in 'A' and 'B' forms, and they showed that the reverse reaction produced glycogen. They won the Nobel Prize in 1947 along with Bernardo Housay of Argentina for their work on carbohydrate metabolism. This was also the first example of a polymerizing enzyme, inspiring others to look for other polymerizing enzymes.		In the 1930s, the first work done by Carl and Gerty Cori. They proved that the enzyme exists in 'A' and 'B' forms, and they showed that the reverse reaction produced glycogen. They won the Nobel Prize in 1947 along with Bernardo Housay of Argentina for their work on carbohydrate metabolism. This was also the first example of a polymerizing enzyme, inspiring others to look for other polymerizing enzymes.

-	Subsequently, Earl Sutherland found that the 'B' form predominates in resting muscle and epinephrine triggers activation to form 'A'. Since then, many groups have worked on this enzyme, both to understand its mechanism and to discover drug targets. Crystal structures have been obtained for the protein in the 'A' and 'B' form, in the presence of natural substrates, inhibitors, and transition state analogs. Please see the end of this article for ~~a list of relevant PDB files, along with a brief description~~.	+	Subsequently, Earl Sutherland found that the 'B' form predominates in resting muscle and epinephrine triggers activation to form 'A'. Since then, many groups have worked on this enzyme, both to understand its mechanism and to discover drug targets. Crystal structures have been obtained for the protein in the 'A' and 'B' form, in the presence of natural substrates, inhibitors, and transition state analogs. Please see the end of this article for links to crystallographic information.

	==Facts about GP==		==Facts about GP==

Max Lein at 07:35, 2 December 2008

2008-12-02T07:35:01Z

←Older revision		Revision as of 07:35, 2 December 2008
Line 15:		Line 15:

	==About this Structure==		==About this Structure==
		+
		+	==Reaction==
		+	Glycogen phosphorylase catalyzes the degradation of glycogen into glucose-1'-phosphate.
		+
		+	==History==
		+	Glycogen phosphorylase was the first phosphorylase enzyme to be discovered, and the first example of regulation via covalent modification.
		+
		+	In the 1930s, the first work done by Carl and Gerty Cori. They proved that the enzyme exists in 'A' and 'B' forms, and they showed that the reverse reaction produced glycogen. They won the Nobel Prize in 1947 along with Bernardo Housay of Argentina for their work on carbohydrate metabolism. This was also the first example of a polymerizing enzyme, inspiring others to look for other polymerizing enzymes.
		+
		+	Subsequently, Earl Sutherland found that the 'B' form predominates in resting muscle and epinephrine triggers activation to form 'A'. Since then, many groups have worked on this enzyme, both to understand its mechanism and to discover drug targets. Crystal structures have been obtained for the protein in the 'A' and 'B' form, in the presence of natural substrates, inhibitors, and transition state analogs. Please see the end of this article for a list of relevant PDB files, along with a brief description.
		+
		+	==Facts about GP==
		+	Protein comes from rabbit muscle tissue, where energy from glucose is needed. There is an isozyme from liver tissue that is regulated by glucagon instead of epinephrine, with a different gene that encodes it and different regulation properties.
		+	Activity and Regulation of GP
		+	1. GP catalyzes the clipping of a glucose molecule off of the reducing end of glycogen. It employs a cofactor called pyridoxal-5’ –phosphate, that is located in the active site and bound to a lysine residue with a Schiff base linkage. PLP shuttles the phosphate group onto the substrate.
		+	2. There are two forms, A and B, and two states, T and R, for the enzyme.
		+	B = nearly inactive dimer, stabilized by electrostatics at N-terminus (w/basic residues) interacting with pocket of acidic residues.
		+	Phosphorylase kinase catalyzes addition of phosphate to Ser14, tightens structure of N-terminal portion of each chain, resulting in conformation change to form A.
		+	Phosphorylation causes electrostatic interference between phosphate group and acidic residues, forcing the N-terminal domain out of the acidic environment and into a region with several arginine side chains.
		+	Phosphatase removes phosphate, returns GP to form B.
		+	Response to hormone epinephrine (in muscle), (fight-or-flight response) or glucagon (in liver), increases available energy to organism as a whole.
		+	- In b form, enzyme can be activated:
		+	Activated by AMP, (cell doesn’t get signal, but needs energy for itself).
		+	Inactivated by ATP, glucose (cell already has enough energy for itself, phosphorylation will not activate)
		+	- Having two overlaid levels of control allows the appropriate response in either situation.
		+	- Phosphoglucomutase shifts carbon chain over 1.
		+
		+
	1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].		1GPA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Additional information on 1GPA is available in a page on [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb24_1.html Glycogen Phosphorylase] at the RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GPA OCA].