"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 the Caspase-12
gene is nonfunctional. 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.
