High-Mobility Group or HMG is a group of

chromosomal A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s that are involved in the regulation of DNA-dependent processes such as transcription, replication, recombination, and

DNA repair DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA d ...

Families

The HMG proteins are subdivided into 3 superfamilies each containing a characteristic functional domain: *

HMGA HMGA is a family of high mobility group proteins characterized by an AT-hook. They code for a "small, nonhistone, chromatin-associated protein that has no intrinsic transcriptional activity but can modulate transcription by altering the chromati ...

– contains an

AT-hook The second AT-hook of HMGA1 (black ribbon) bound to the minor-groove of AT-rich DNA. The amino-acid side chains and nucleotides have been hidden. The AT-hook is a DNA-binding motif present in many proteins, including the high mobility group (HM ...

domain **

HMGA1 High-mobility group protein HMG-I/HMG-Y is a protein that in humans is encoded by the ''HMGA1'' gene. Function This gene encodes a non-histone chromatin protein involved in many cellular processes, including regulation of inducible gene transc ...

** HMGA2 * HMGB – contains a

HMG-box In molecular biology, the HMG-box (high mobility group box) is a protein domain which is involved in DNA binding. Structure The structure of the HMG-box domain contains three alpha helices separated by loops (see figure to the right). Function ...

domain **

HMGB1 High mobility group box 1 protein, also known as high-mobility group protein 1 (HMG-1) and amphoterin, is a protein that in humans is encoded by the ''HMGB1'' gene. HMG-1 belongs to the high mobility group and contains a HMG-box domain. Functi ...

HMGB2 High-mobility group protein B2 also known as high-mobility group protein 2 (HMG-2) is a protein that in humans is encoded by the ''HMGB2'' gene. Function This gene encodes a member of the non-histone chromosomal high-mobility group protein fa ...

HMGB3 High-mobility group protein B3 is a protein that in humans is encoded by the ''HMGB3'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generatio ...

** HMGB4 *

HMGN HMGN (High Mobility Group Nucleosome-binding) proteins are members of the broader class of high mobility group (HMG) chromosomal proteins that are involved in regulation of Transcription (biology), transcription, DNA replication, replication, Genet ...

– contains a nucleosomal binding domain ** HMGN1 ** HMGN2 ** HMGN3 **

HMGN4 High mobility group nucleosome-binding domain-containing protein 4 is a transcription factor that in humans is encoded by the ''HMGN4'' gene. Function The protein encoded by this gene, a member of the HMGN protein family, is thought to reduce ...

** HMGN5 Proteins containing any of these embedded in their sequence are known as HMG motif proteins.

proteins are found in a variety of

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

organisms. They were originally isolated from

mammalian Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fu ...

cells, and named according to their electrophoretic mobility in

polyacrylamide Polyacrylamide (abbreviated as PAM) is a polymer with the formula (-CH2CHCONH2-). It has a linear-chain structure. PAM is highly water-absorbent, forming a soft gel when hydrated. In 2008, an estimated 750,000,000 kg were produced, mainly fo ...

gels.

Other families with HMG-box domain

SOX gene family ''SOX'' genes ('' SRY''-related HMG-box genes) encode a family of transcription factors that bind to the minor groove in DNA, and belong to a super-family of genes characterized by a homologous sequence called the HMG-box (for high mobilit ...

** Sex-Determining Region Y Protein ** SOX1, SOX2, etc. *

TCF/LEF family The TCF/LEF family (T cell factor/lymphoid enhancer factor family) is a group of genes that encode transcription factors which bind to DNA through a SOX-like high mobility group domain. They are involved in the Wnt signaling pathway The Wnt sig ...

(T cell factor/lymphoid enhancer factor family) ** LEF1 ( Lymphoid enhancer-binding factor 1) ** TCF7 (TCF-1) ** TCF7L1 (TCF-3) **

TCF7L2 Transcription factor 7-like 2 (T-cell specific, HMG-box), also known as TCF7L2 or TCF4, is a protein acting as a transcription factor that, in humans, is encoded by the ''TCF7L2'' gene. The TCF7L2 gene is located on chromosome 10q25.2–q25.3, con ...

(TCF-4)

Function

HMG proteins are thought to play a significant role in various human disorders. Disruptions and rearrangements in the genes coding for some of the HMG proteins are associated with some common benign tumors.

Antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of ...

to HMG proteins are found in patients with

autoimmune In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". ...

diseases. The SRY gene on the Y Chromosome, responsible for male sexual differentiation, contains an HMG-Box domain. A member of the HMG family of proteins,

, has also been shown to have an extracellular activity as a

chemokine Chemokines (), or chemotactic cytokines, are a family of small cytokines or signaling proteins secreted by cells that induce directional movement of leukocytes, as well as other cell types, including endothelial and epithelial cells. In additi ...

, attracting

neutrophils Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying ...

and mononuclear inflammatory cells to the infected

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

. The high-mobility group protein such as HMO1 alters DNA architecture by binding, bending and looping. Furthermore, these

DNA-binding proteins DNA-binding proteins are proteins that have DNA-binding domains and thus have a specific or general affinity for DNA#Base pairing, single- or double-stranded DNA. Sequence-specific DNA-binding proteins generally interact with the major groove ...

increase the flexibility of the DNA upon binding.

References

External links

HMG nomenclature home page
* Gene expression Transcription factors {{genetics-stub

Families

Other families with HMG-box domain

Function

See also

References

External links