"New Genome
Comparison Finds
Chimps, Humans Very Similar at the DNA Level":
How are they different?
Caspases are
a
family of proteins that act as mediators of apoptosis (programmed
cell-death),
in
which cells die as a normal part of tissue development and
differentiation. In chimpanzees, a particular DNA sequence is recognizable
as an open reading frame
that includes a
functional motif (the SHG box) common to other
caspase
genes. This locus is inferred to be a functional gene, designated
Caspase-12.
In the human DNA sequence
at the analogous
chromosome position, this reading frame is interrupted by a nonsense
mutation, and the SHG
box
is
altered as well, such that there is no functional Caspase-12 gene. Absence of
a functional protein has been implicated in Alzheimer
Disease: analogous mutations in a mouse model interfere
with
normal amyloid-induced neuronal apoptosis and disrupt calcium
homeostasis, both characteristics of the disease.
