This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
User:Alice Harmon/EF Hand
From Proteopedia
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.
3HX4 |
1prw |
4cpv |
