User:Alice Harmon/EF Hand: Difference between revisions
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| <applet load=' | | <applet load='4cpv' size='300' frame='true' align='right' caption='4cpv - Carp parvalbumin' scene='56/562354/Parvalbumin/1' /><Br>'''4cpv''' <Br><scene name='56/562354/Parvalbumin/2'>1. Pair of EF-hands</scene> | ||
| <applet load=' | | <applet load='1prw' size='300' frame='true' align='right' caption='1prw - Bovine calmodulin' scene='56/562354/Calmodulin/1' /><Br>'''1prw''' <Br><scene name='56/562354/Calmodulin/3'>1. Pair of EF hands</scene><br><scene name='56/562354/Calmodulin/4'>EF hand I</scene> | ||
| <applet load='3HX4' size='300' frame='true' align='left' caption='3hx4 - active TgCDPK1' scene = '56/562354/Cdpk/1' /><Br>'''3HX4'''<Br><scene name='56/562354/Cdpk_ef_hand_pair/2'>1. Pair of EF hands</scene><br><scene name='56/562354/Cdpk_ef_iv/1'>2. EF Hand IV</scene><br><scene name='56/562354/Cdpk_ef_iv/2'>3. Calcium-binding ligands</scene> | |||
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Revision as of 18:38, 20 September 2013
EF-hands are calcium-binding motifs found in hundreds of proteins. They bind calcium ions with high affinity (Kds are in the micromolar range) and selectivity, and this property allows EF-hand proteins to sense changes in intracellular calcium. In unstimulated cells cellular free calcium concentrations [Ca2+]c are in the nanomolar range (~10 nM in animal cells and ~200 nM in plant cells), and EF-hands are generally unoccupied by Ca2+. Upon stimulation, Ca2+ enters the cytosol from either outside the cell or from internal organelles, and [Ca2+]c rises to the micromolar range. EF-hands bind Ca2+, and this binding causes a conformational change that alters the activity of the protein.
The name EF-hand originated from the first such structure to be described, which was in the protein parvalbumin. In this protein calcium is bound by a helix-loop-helix structure that is formed by the E and F helices (letters assigned to helices in the order that they occur starting at the N-terminus). See the annotated protein sequence for carp parvalbumin here [1].
Below are EF-hands found in parvalbumin, calmodulin, and calcium-dependent protein kinase.
4cpv |
1prw |
3HX4 |