A hypervariable region (HVR) is a location within

nuclear DNA Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. I ...

or the

D-loop In molecular biology, a displacement loop or D-loop is a DNA structure where the two strands of a double-stranded DNA molecule are separated for a stretch and held apart by a third strand of DNA. An R-loop is similar to a D-loop, but in this ca ...

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

in which

base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both D ...

s of

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecu ...

s repeat (in the case of nuclear DNA) or have substitutions (in the case of mitochondrial DNA). Changes or repeats in the hypervariable region are highly polymorphic.

Mitochondrial

There are two MITOCHONDRIAL hypervariable regions used in human mitochondrial

genealogical DNA test A genealogical DNA test is a DNA-based test used in genetic genealogy that looks at specific locations of a person's genome in order to find or verify ancestral genealogical relationships, or (with lower reliability) to estimate the ethnic mixt ...

ing. HVR1 is considered a "low resolution" region and HVR2 is considered a "high resolution" region. Getting HVR1 and HVR2 DNA tests can help determine one's

haplogroup A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup (haploid from the el, ἁπλοῦς, ''haploûs'', "onefold, simple" and en, group) is a group of similar haplotypes that share ...

. In the revised

Cambridge Reference Sequence The Cambridge Reference Sequence (CRS) for human mitochondrial DNA was first announced in 1981. A group led by Fred Sanger at the University of Cambridge had sequenced the mitochondrial genome of one woman of European descent during the 1970s, ...

of the human mitogenome, the most variable sites of HVR1 are numbered 16024-16383 (this subsequence is called HVR-I), and the most variable sites of HVR2 are numbered 57-372 (''i.e.,'' HVR-II) and 438-574 (''i.e.,'' HVR-III).''PhyloTree mt''
"Annotated mtDNA reference sequences: revised Cambridge Reference Sequence (rCRS)"
Retrieved on 4 February 2016. In some

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartil ...

es, for example certain

Protacanthopterygii Protacanthopterygii is a ray-finned fish taxon ranked as a superorder of the infraclass Teleostei. They inhabit both marine and freshwater habitats. They appear to have evolved in the Cretaceous or perhaps late Jurassic, originating probably roug ...

and

Gadidae The Gadidae are a family of marine fish, included in the order Gadiformes, known as the cods, codfishes, or true cods. It contains several commercially important fishes, including the cod, haddock, whiting, and pollock. Most gadid species ...

, the mitochondrial control region evolves remarkably slowly. Even functional mitochondrial

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

s accumulate mutations faster and more freely. It is not known whether such hypovariable control regions are more widespread. In the Ayu (''Plecoglossus altivelis''), an

East Asia East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea ...

n protacanthopterygian, control region

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, m ...

rate is not markedly lowered, but sequence differences between

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

are far lower in the control region than elsewhere. This phenomenon completely defies explanation at present.Takeshima, Hirohiko; Iguchi, Kei-ichiro & Nishida, Mutsumi (2005): Unexpected Ceiling of Genetic Differentiation in the Control Region of the Mitochondrial DNA between Different Subspecies of the Ayu ''Plecoglossus altivelis''. '' Zool. Sci.'' 22(4): 401–410. (HTML abstract)

Antibodies

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 ...

, hypervariable regions form the antigen-binding site and are found on both

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

and heavy chains. They also contribute to the specificity of each antibody. In a

variable domain 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 ...

, the 3 H_V segments of each heavy or light chain fold together at the

N-terminus The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...

to form an antigen binding pocket.

References

External links

* {{MeshName, Hypervariable+region
DNA: Forensic and Legal Applications, Explanation of Hypervariable Regions
Genetic genealogy Genetic engineering Antibodies

Mitochondrial

Antibodies

See also

References

External links