MYH16 gene

The MYH16 gene encodes a protein called myosin heavy chain 16 which is a muscle protein in mammals. At least in primates, it is a specialized muscle protein found only in the temporalis and masseter muscles of the jaw.cite book |author=Carroll, Sean B. |title=Endless forms most beautiful: the new science of evo-devo and the making of the animal kingdom |publisher=Norton |location=New York |year=2005 |pages=272–274 |isbn=0-393-32779-5 ] cite journal | author = Stedman, H.H.; Kozyak, B.W.; Nelson, A.; Thesier, D.M.; Su, L.T.; Low, D.W.; Bridges, C.R.; Shrager, J.B.; Purvis, N.M. & Mitchell, M.A. | title = Myosin gene mutation correlates with anatomical changes in the human lineage | journal = Nature | volume = 428 | issue = 6981 | pages = 415–418 | doi = 10.1038/nature02358 | pmid = 15042088 | date = 25 Mar 2004] Myosin heavy chain proteins are important in muscle contraction, and if they are missing, the muscles will be smaller. In non-human primates, MYH16 is functional and the animals have powerful jaw muscles. In humans, the MYH16 gene has a mutation which causes the protein not to function. [cite journal | journal = Proc Natl Acad Sci U S A. | date = 2006 April 11 | volume = 103 | issue = 15 | pages = 5676–5681 | doi = 10.1073/pnas.0509562103 | url = http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1458632 | title = Natural selection and molecular evolution in primate PAX9 gene, a major determinant of tooth development | author = Tiago V. Pereira, Francisco M. Salzano, Adrianna Mostowska, Wieslaw H. Trzeciak, Andrés Ruiz-Linares, José A. B. Chies, Carmen Saavedra, Cleusa Nagamachi, Ana M. Hurtado, Kim Hill, Dinorah Castro-de-Guerra, Wilson A. Silva-Júnior, and Maria-Cátira Bortolini | pmid = 16585527 ] Although the exact importance of this change in accounting for differences between humans and apes is not yet clear, such a change may be related to increased brain size and finer control of the jaw which facilitates speech. It is not clear how the MYH16 mutation relates to other changes to the jaw and skull in early human evolution (for example, whether the MYH16 mutation happened first and led to other changes, or whether the MYH16 mutation happened after other changes made the MYH16 protein no longer necessary).

The initial discovery of the human MYH16 mutation was published in 2004 by a team at the University of Pennsylvania led by Hansell H. Stedman. The date of the mutation has variously been estimated at about 2.4 million years ago or 5.3 million years ago.cite journal | author = Perry, G.H.; Verrelli, B.C. & Stone, A.C. | year = 2005 | title = Comparative analyses reveal a complex history of molecular evolution for human MYH16 | journal = Mol Biol Evol | volume = 22 | issue = 3 | pages = 379–382 | doi = 10.1093/molbev/msi004 | pmid = 15470226 | url = http://mbe.oxfordjournals.org/cgi/content/full/22/3/379 ]

The MYH16 gene is present in dogs, but does not appear to be present in mice. [cite journal | url = http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2134963 | journal = PLoS Comput Biol. | date = 2007 December | volume = 3 | issue = 12 | pages = e247 | doi = 10.1371/journal.pcbi.0030247 | title = Comparative Genomics Search for Losses of Long-Established Genes on the Human Lineage | author = Jingchun Zhu1, J. Zachary Sanborn, Mark Diekhans, Craig B. Lowe, Tom H. Pringle, David Haussler | pmid = 18085818 ]

References

External links

* [http://www.sciscoop.com/story/2004/3/24/65831/0337 Story from Science Scoop]
* [http://www.nature.com/nsu/040322/040322-9.html Nature article, "Jaw-dropping theory of human evolution"]