Sandbox Reserved 970: Difference between revisions

Line 27:

The structure on the left is the empty state (free from calcium). Two calcium ions are shown in blue and Asp351 is shown in red.<ref name="second"> David Goodsell, 2004 - Calcium pump molecul of the month - PDB, doi: 10.2210/rcsb_pdb/mom_2004_3</ref>

To sum up, calcium pumps have two conformations, E1 and E2. These two conformations are characterized by different specificity for ion binding. When the pump is in the E1 state, it has high calcium affinity and interacts with calcium at one side of the membrane. In the E2 state, the enzyme has a lower calcium affinity and that leads to the release of the ion at the opposite side. E1 has the calcium binding site oriented toward the cytoplasm. E2 has the calcium binding site oriented toward the lumen of the endoplasmic reticulum or toward the extracellular ~~background~~<ref name="third">Thomas D.Pollard and William C. Earnshaw, - ''Membrane, structure and function'' - Cell Biology (second edition), p.133-136</ref>. The phosphorylated intermediate, E1 can phosphorylate ADP, whereas E2 can only react with water<ref>David H.MacLennan, William J.Rice and N. Michael Green, 1997 - ''The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases'' - The Journal of Biological Chemistry, p.272, 28815-28818, http://www.jbc.org/content/272/46/28815.full.html</ref>. In the absence of calcium, calcium pumps are mainly in E1 state.

To sum up, calcium pumps have two conformations, E1 and E2. These two conformations are characterized by different specificity for ion binding. When the pump is in the E1 state, it has high calcium affinity and interacts with calcium at one side of the membrane. In the E2 state, the enzyme has a lower calcium affinity and that leads to the release of the ion at the opposite side. E1 has the calcium binding site oriented toward the cytoplasm. E2 has the calcium binding site oriented toward the lumen of the endoplasmic reticulum or toward the extracellular space<ref name="third">Thomas D.Pollard and William C. Earnshaw, - ''Membrane, structure and function'' - Cell Biology (second edition), p.133-136</ref>. The phosphorylated intermediate, E1 can phosphorylate ADP, whereas E2 can only react with water<ref>David H.MacLennan, William J.Rice and N. Michael Green, 1997 - ''The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases'' - The Journal of Biological Chemistry, p.272, 28815-28818, http://www.jbc.org/content/272/46/28815.full.html</ref>. In the absence of calcium, calcium pumps are mainly in E1 state.

Sandbox Reserved 970: Difference between revisions

Navigation menu

Page actions

Page actions

Personal tools

Navigation

Search

Tools

Revision as of 20:01, 9 January 2015 view source Elodie Sévère (talk \| contribs) 61 edits No edit summary ← Older edit		Revision as of 20:04, 9 January 2015 view source Elodie Sévère (talk \| contribs) 61 edits No edit summary Newer edit →
Line 27:		Line 27:
	The structure on the left is the empty state (free from calcium). Two calcium ions are shown in blue and Asp351 is shown in red.<ref name="second"> David Goodsell, 2004 - Calcium pump molecul of the month - PDB, doi: 10.2210/rcsb_pdb/mom_2004_3</ref>		The structure on the left is the empty state (free from calcium). Two calcium ions are shown in blue and Asp351 is shown in red.<ref name="second"> David Goodsell, 2004 - Calcium pump molecul of the month - PDB, doi: 10.2210/rcsb_pdb/mom_2004_3</ref>

	To sum up, calcium pumps have two conformations, E1 and E2. These two conformations are characterized by different specificity for ion binding. When the pump is in the E1 state, it has high calcium affinity and interacts with calcium at one side of the membrane. In the E2 state, the enzyme has a lower calcium affinity and that leads to the release of the ion at the opposite side. E1 has the calcium binding site oriented toward the cytoplasm. E2 has the calcium binding site oriented toward the lumen of the endoplasmic reticulum or toward the extracellular ~~background~~<ref name="third">Thomas D.Pollard and William C. Earnshaw, - ''Membrane, structure and function'' - Cell Biology (second edition), p.133-136</ref>. The phosphorylated intermediate, E1 can phosphorylate ADP, whereas E2 can only react with water<ref>David H.MacLennan, William J.Rice and N. Michael Green, 1997 - ''The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases'' - The Journal of Biological Chemistry, p.272, 28815-28818, http://www.jbc.org/content/272/46/28815.full.html</ref>. In the absence of calcium, calcium pumps are mainly in E1 state.		To sum up, calcium pumps have two conformations, E1 and E2. These two conformations are characterized by different specificity for ion binding. When the pump is in the E1 state, it has high calcium affinity and interacts with calcium at one side of the membrane. In the E2 state, the enzyme has a lower calcium affinity and that leads to the release of the ion at the opposite side. E1 has the calcium binding site oriented toward the cytoplasm. E2 has the calcium binding site oriented toward the lumen of the endoplasmic reticulum or toward the extracellular space<ref name="third">Thomas D.Pollard and William C. Earnshaw, - ''Membrane, structure and function'' - Cell Biology (second edition), p.133-136</ref>. The phosphorylated intermediate, E1 can phosphorylate ADP, whereas E2 can only react with water<ref>David H.MacLennan, William J.Rice and N. Michael Green, 1997 - ''The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases'' - The Journal of Biological Chemistry, p.272, 28815-28818, http://www.jbc.org/content/272/46/28815.full.html</ref>. In the absence of calcium, calcium pumps are mainly in E1 state.