The highly conserved centromere-associated protein CENP-B is a common
feature of mammalian centromeres. Binding sites for CENP-B, so-called
'CENP-B boxes', are present in the otherwise unrelated centromeric sat
ellite DNAs of humans, Mus musculus, Mus caroli, ferrets, giant pandas
, tree shrews and gerbils, suggesting a role for CENP-B in centromere
function. However, CENP-B and its binding sites are not detected at th
e centromeres of mammalian Y chromosomes and few, if any, binding site
s seem present on African green monkey chromosomes. There is extensive
sequence similarity between CENP-B and transposase proteins encoded b
y the pogo superfamily of transposable elements, which includes the hu
man Tigger elements. Intriguingly, Tigger 2 has an almost perfect matc
h to the CENP-B-binding site within its terminal inverted repeat. Comp
arison of the amino acid sequence of CENP-B with related proteins rais
es the possibility that CENP-B might share the ability to cause single
-stranded DNA breaks. Such nicks could promote recombination, as has b
een suggested for the Charcot-Marie-Tooth disease duplication where a
recombination hotspot exists close to a mariner-like element. We sugge
st that by promoting nicks adjacent to CENP-B boxes, CENP-B might faci
litate the evolution and maintenance of satellite sequence arrays, rat
her than have a direct role in centromere function.