Globin

A family of proteins involved in oxygen transport and storage

Globin is a family of proteins that play a crucial role in the transport and storage of oxygen in various organisms. These proteins are characterized by their ability to bind oxygen molecules, a function that is essential for the survival of aerobic life forms. Globins are found in a wide range of species, from bacteria to humans, and are integral components of hemoglobin and myoglobin.

Structure

Globins are typically composed of a series of alpha helices that form a globular structure. This structure is stabilized by hydrophobic interactions and hydrogen bonds. The core of the globin protein contains a heme group, which is responsible for binding oxygen. The heme group consists of an iron ion held within a porphyrin ring, allowing it to reversibly bind oxygen molecules.

Function

The primary function of globins is to facilitate the transport and storage of oxygen. In vertebrates, hemoglobin is the most well-known globin, responsible for transporting oxygen from the lungs to tissues throughout the body. Myoglobin, another type of globin, is found in muscle tissues and serves to store oxygen, providing a reserve during periods of intense muscular activity.

Oxygen Binding

The ability of globins to bind oxygen is due to the presence of the heme group. When oxygen binds to the iron ion in the heme, it causes a conformational change in the protein, enhancing its affinity for additional oxygen molecules. This cooperative binding is a key feature of hemoglobin, allowing it to efficiently load and unload oxygen as needed.

Types of Globins

Globins are classified into several types based on their structure and function:

• Hemoglobin: Found in red blood cells, responsible for oxygen transport.
• Myoglobin: Found in muscle cells, responsible for oxygen storage.
• Neuroglobin: Found in the brain and nervous system, thought to protect neurons from hypoxia.
• Cytoglobin: Found in various tissues, its exact function is still under investigation.

Evolution

Globins have a long evolutionary history, with evidence suggesting that they originated from a common ancestral gene. Over time, gene duplication and divergence have led to the variety of globins observed today. This evolutionary process has allowed globins to adapt to the specific oxygen transport and storage needs of different organisms.

Clinical Significance

Mutations in globin genes can lead to a variety of hemoglobinopathies, such as sickle cell disease and thalassemia. These conditions result from abnormal globin protein structure or function, leading to impaired oxygen transport and various clinical symptoms.

Related pages

• Hemoglobin
• Myoglobin
• Heme
• Oxygen transport
• Hemoglobinopathy

Globin

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  PDB 1hba EBI

• PDB 1s56 EBI