Satellite DNA

Satellite DNA is a repetitive DNA sequence that originates a satellite band in a density gradient, consisting on non-coding DNA.

This is the major component of functional centromeres, being also the main structural component in heterochromatin.

Its GC content is different from the genome standard, which makes these fragments present different buoyant densities from those shown in single-copy DNA, therefore it migrates to different positions in the density gradient.

Satellite DNA is divided into 5 types:


α, which lenght is about 171 bp (base pairs) and is found in all chromossomes;

β, with 68 bp, is commonly found in centromeres of chromosomes 1, 9, 13, 14, 15, 21, 22 and Y;

Satellite 1, with 25-48 bp, is commonly present in centromeres and other regions in heterochromatin of most chromosomes;

Satellite 2 and 3 , both with 5 bp, can be found in most chromossomes.