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Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres , and form the main structural constituent of heterochromatin .
In most eukaryotes, the centromere's DNA sequence consists of large arrays of repetitive DNA (e.g. satellite DNA) where the sequence within individual repeat elements is similar but not identical. In humans, the primary centromeric repeat unit is called α-satellite (or alphoid), although a number of other sequence types are found in this ...
Centromere protein A, also known as CENPA, is a protein which in humans is encoded by the CENPA gene. [5] CENPA is a histone H3 variant which is the critical factor determining the kinetochore position(s) on each chromosome [ 6 ] in most eukaryotes including humans.
Centromeres are composed of a 177 base pair tandem repeat named the α-satellite repeat. [16] Pericentromeric heterochromatin, the DNA which surrounds the centromere and is important for structural maintenance, is composed of a mixture of different satellite subfamilies including the α-, β- and γ-satellites as well as HSATII, HSATIII, and ...
Satellite chromosomes or SAT-chromosomes are chromosomes that contain secondary constructs that serve as identification. They are observed in acrocentric chromosomes. In addition to the centromere , one or more secondary constrictions can be observed in some chromosomes at metaphase .
The DNA binding domain recognizes and binds a 17-bp sequence (CENP-B box) in the centromeric alpha satellite DNA. This protein is proposed to play an important role in the assembly of specific centromere structures in interphase nuclei and on mitotic chromosomes.
Human centromeres usually consist of 2000–4000 kilobases of a 171 base pair repeat unit. This alpha satellite is not present at all in human neocentromeres. [10] By 2008, more than 90 reported cases of human neocentromeres were detected on marker chromosomes that experienced a loss of centromere, and a subsequent rearrangement. [10]
Centric heterochromatin is usually formed on alpha satellite DNA in humans; however, there have been cases where centric heterochromatin and centromeres have formed on originally euchromatin domains lacking alpha satellite DNA; this usually happens as a result of a chromosome breakage event and the formed centromere is called a neocentromere. [1]