Which of the following proteins has a structural motif called an EF hand?

Which of the following proteins has a structural motif called an EF hand?

The EF hand is a helix–loop–helix structural domain or motif found in a large family of calcium-binding proteins.

How many EF hands in calmodulin?

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 is meant by an EF hand?

EF hand. 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.

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 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.

How is calmodulin activated?

Activation. Calmodulin is activated by intracellular calcium. When calcium concentrations rise, the calcium ions are able to bind to calmodulin at a special motif called an EF hand domain. This configuration of amino acids is characteristic of calcium-binding proteins.

Does calmodulin have an EF-hand?

As a prototypical EF-hand protein, calmodulin (CaM) contains four Ca2+ binding EF-hand motifs: EF-1 and EF-2 associate to form its N-domain, and EF-3 and EF-4 associate to form its C-domain. The arrangement of EF-hands in CaM is thought to be a consequence of its evolution from a progenitor EF-hand by gene duplication.

Where is troponin C found?

muscle
Troponin C, also known as TN-C or TnC, is a protein that resides in the troponin complex on actin thin filaments of striated muscle (cardiac, fast-twitch skeletal, or slow-twitch skeletal) and is responsible for binding calcium to activate muscle contraction.

What is helix loop helix motif?

A basic helix–loop–helix (bHLH) is a protein structural motif that characterizes one of the largest families of dimerizing transcription factors. bHLH transcription factors are often important in development or cell activity. For one, BMAL1-Clock is a core transcription complex in the molecular circadian clock.

How does calcium activate calmodulin?

It is an intracellular target of the secondary messenger Ca2+, and the binding of Ca2+ is required for the activation of calmodulin. Once bound to Ca2+, calmodulin acts as part of a calcium signal transduction pathway by modifying its interactions with various target proteins such as kinases or phosphatases.

What are the two major groups of EF-hands?

EF-hand motifs are divided into two major groups: Canonical EF-hands as seen in calmodulin (CaM) and the prokaryotic CaM-like protein calerythrin. The 12-residue canonical EF-hand loop binds Ca 2+ mainly via sidechain carboxylates or carbonyls (loop sequence positions 1, 3, 5, 12).

What are the functions of the EF hand?

Single EF-hand motifs can serve as protein-docking modules: for example, the single EF hand in the NKD1 and NKD2 proteins binds the Dishevelled (DVL1, DVL2, DVL3) proteins. Functionally, the EF-hands can be divided into two classes: 1) signaling proteins and 2) buffering/transport proteins.

How are EF hand proteins related to each other?

EF-hand proteins contain two to 12 tandem copies of the EF-hand domain. EF-hands occur in pairs, EF-lobe, and are related by an approximate twofold axis of rotation (Fig. 2).

Is there a pattern to predict canonical EF hand?

Based on the sequence alignment results of canonical EF-hand motifs, especially the conserved side chains directly involved in Ca 2+ binding, a pattern PS50222 has been generated to predict canonical EF-hand sites. A prediction servers may be found in the external links section.