Gilad Yoav, Man Orna, Pääbo Svante, Lancet Doron
Max Planck Institute for Evolutionary Anthropology, Inselstrasse 22, Leipzig D-04103, Germany.
Proc Natl Acad Sci U S A. 2003 Mar 18;100(6):3324-7. doi: 10.1073/pnas.0535697100. Epub 2003 Feb 28.
Olfactory receptor (OR) genes constitute the basis for the sense of smell and are encoded by the largest mammalian gene superfamily of >1,000 genes. In humans, >60% of these are pseudogenes. In contrast, the mouse OR repertoire, although of roughly equal size, contains only approximately 20% pseudogenes. We asked whether the high fraction of nonfunctional OR genes is specific to humans or is a common feature of all primates. To this end, we have compared the sequences of 50 human OR coding regions, regardless of their functional annotations, to those of their putative orthologs in chimpanzees, gorillas, orangutans, and rhesus macaques. We found that humans have accumulated mutations that disrupt OR coding regions roughly 4-fold faster than any other species sampled. As a consequence, the fraction of OR pseudogenes in humans is almost twice as high as in the non-human primates, suggesting a human-specific process of OR gene disruption, likely due to a reduced chemosensory dependence relative to apes.
嗅觉受体（OR）基因构成了嗅觉的基础，由超过1000个基因组成的最大的哺乳动物基因超家族编码。在人类中，其中超过60%是假基因。相比之下，小鼠的OR基因库虽然大小大致相同，但仅包含约20%的假基因。我们询问非功能性OR基因的高比例是人类特有的，还是所有灵长类动物的共同特征。为此，我们将50个人类OR编码区的序列（无论其功能注释如何）与其在黑猩猩、大猩猩、猩猩和恒河猴中假定的直系同源序列进行了比较。我们发现，人类积累的破坏OR编码区的突变速度比其他任何采样物种快约4倍。因此，人类中OR假基因的比例几乎是非人类灵长类动物的两倍，这表明OR基因破坏是一个人类特有的过程，可能是由于相对于猿类，化学感觉依赖性降低所致。
