How many EF hands does calmodulin have?

two EF hand pairs
Calmodulin (CaM) is a cytosolic Ca2+-binding protein that serves as a control element for many enzymes. It consists of two globular domains, each containing two EF hand pairs capable of binding Ca2+, joined by a flexible central linker region.

What does EF hand stand for?

EF hands are calcium-binding motifs found in hundreds of proteins. 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).

What is an EF domain?

The adjacent end of α-spectrin, called the EF domain, is calmodulin-like, with calcium-dependent and calcium-independent EF hands. The data show that the α-spectrin EF domain greatly amplifies the function of the β-spectrin actin-binding domain (ABD) in forming the spectrin-actin-4.1R complex.

What do calcium binding proteins do?

Calcium-binding proteins are proteins that participate in calcium cell signalling pathways by binding to Ca2+, the calcium ion that plays an important role in many cellular processes. The cellular regulation of calcium is known as calcium homeostasis. …

What contains EF-hands that bind ca2+?

Aequorin is made up of two components – the calcium binding component apoaequorin (AQ) and the chemiluminescent molecule coelenterazine. The AQ portion of this protein contains the EF-hand calcium binding domains.

What is a recognition helix?

In most cases, such as in the Cro repressor, the second helix contributes most to DNA recognition, and hence it is often called the “recognition helix”. It binds to the major groove of DNA through a series of hydrogen bonds and various Van der Waals interactions with exposed bases.

Where is calmodulin found?

Calcium ions play very important roles in functions such as sending nerve signals and muscle contraction. Calmodulin is a calcium-modulated protein. It is found in many types of cells and is located in the cytoplasm, inside organelles, or within membranes.

Does calcium bind to troponin or tropomyosin?

If present, calcium ions bind to troponin, causing conformational changes in troponin that allow tropomyosin to move away from the myosin-binding sites on actin.

Which protein attaches to calcium during muscle contraction?

Troponin plays a central role in the calcium-regulation of muscle contraction: Troponin is the sole calcium-binding component of thin filaments (actin-tropomyosin-troponin complex) of striated muscles.

Which is the calcium-binding site?

Calcium-binding protein: Any protein or enzyme that requires the binding of a calcium ion to fulfill either a functional or structural role. Binding site: Region in the protein where metal ions will bind as a result of electrostatic interactions with ligands of opposite charge.

How many binding sites does troponin have?

The muscle protein troponin-C (TnC) contains four calcium-binding sites arranged as a pair of two-site domains.

What is the EF-hand domain used for?

It is not unusual for a basic protein domain to find many uses, often spliced together with other domains; however, the EF-hand is one of the most widely distributed domains in eukaryotes, perhaps reflecting the range and subtlety of calcium signaling.

How does the EF hand domain interact with the adjacent subunit?

In both proteins, the EF hand domain is thought to interact with the adjacent actin-binding CH domain on the neighboring subunit.

Does the EF-hand domain play a role in RyR2 function?

Although the role of the EF-hand domain in RyR1 function has been studied extensively, little is known about the functional significance of the corresponding EF-hand domain in RyR2. Here we investigate the effect of mutations in the EF-hand motifs on the Ca(2+) activation of RyR2.

What are EF-hand proteins?

In PLCε, the EF hands interact with the first C-terminal Ras association (RA) domain, as well as the TIM barrel and C2 domains (Rugema et al., 2020). Robert H. Kretsinger, Jason E. Schaffer, in Encyclopedia of Biological Chemistry (Third Edition), 2021 EF-hand proteins contain two to 12 tandem copies of the EF-hand domain.