Hemoglobin

Hemoglobin and myoglobin are the oxygentransporting
proteins in vertebrates. Hemoglobin
is found in red blood cells, myoglobin in
muscle. Hemoglobin arose from myoglobin
during the course of evolution. Hemoglobin has
four oxygen-binding sites, myoglobin has one.
Their genes and their three-dimensional protein
structures are completely known in atomic
detail. Different types of hemoglobin that are
optimally adapted to prenatal and postnatal life
have evolved in mammals from an ancestral
gene.