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 are ...
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, respo ...
s that are involved in the regulation of DNA-dependent processes such as
transcription
Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including:
Genetics
* Transcription (biology), the copying of DNA into RNA, the fir ...
,
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 dam ...
.
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 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
High-mobility group AT-hook 2, also known as HMGA2, is a protein that, in humans, is encoded by the ''HMGA2'' gene.
Function
This gene encodes a protein that belongs to the non-histone chromosomal high-mobility group (HMG) protein family. HMG ...
* 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
Non-histone chromosomal protein HMG-14 is a protein that in humans is encoded by the ''HMGN1'' gene.
Function
Chromosomal protein HMG14 and its close analog HMG17 (MIM 163910) bind to the inner side of the nucleosomal DNA, potentially alteri ...
**
HMGN2
Non-histone chromosomal protein HMG-17 is a protein that in humans is encoded by the ''HMGN2'' gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''g ...
**
HMGN3
High mobility group nucleosome-binding domain-containing protein 3 is a protein that in humans is encoded by the ''HMGN3'' gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units ...
**
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.
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
...
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 (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...
cells, and named according to their
electrophoretic
Electrophoresis, from Ancient Greek ἤλεκτρον (ḗlektron, "amber") and φόρησις (phórēsis, "the act of bearing"), is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric fi ...
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 f ...
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 mobility g ...
**
Sex-Determining Region Y Protein
**
SOX1
SOX1 is a gene that encodes a transcription factor with a HMG-box (high mobility group) DNA-binding domain and functions primarily in neurogenesis. SOX1, SOX2 and SOX3, members of the SOX gene family (specifically the SOXB1 group), contain tra ...
,
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
Lymphoid enhancer-binding factor 1 (LEF1) is a protein that in humans is encoded by the ''LEF1'' gene. It's a member of T cell factor/lymphoid enhancer factor ( TCF/LEF) family.
Function
Lymphoid enhancer-binding factor-1 (LEF1) is a 48-kD nu ...
)
**
TCF7
Transcription factor 7 is the gene that in humans encodes for the TCF1 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 w ...
(TCF-1)
**
TCF7L1
Transcription factor 7-like 1, also known as TCF7L1, is a human gene.
This gene encodes a member of the T cell factor/lymphoid enhancer factor family of transcription factors. These transcription factors are activated by beta catenin, mediate t ...
(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 the ...
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". P ...
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,
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 ...
, 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 additio ...
, 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 in ...
and mononuclear inflammatory cells to the infected
liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
.
The high-mobility group protein such as HMO1 alters DNA architecture by binding, bending and looping. Furthermore, these
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
...
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.
See also
*
Gene regulatory network
A gene (or genetic) regulatory network (GRN) is a collection of molecular regulators that interact with each other and with other substances in the cell to govern the gene expression levels of mRNA and proteins which, in turn, determine the fun ...
*
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
...
*
Transcription factors
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The func ...
References
External links
HMG nomenclature home page*
Gene expression
Transcription factors
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