MYH16 gene explained

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.^{[1] [2]} Myosin heavy chain proteins are important in muscle contraction, and if they are missing, the muscles will be smaller.^[1] In non-human primates, MYH16 is functional and the animals have powerful jaw muscles. In humans, the MYH16 gene has a mutation that causes the protein not to function.^[3] Although the exact importance of this change in accounting for differences between humans and other apes is not yet clear, such a change may be related to increased brain size and finer control of the jaw, which facilitates speech.^[1] 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).^[1]

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.^[2] The date of the mutation has variously been estimated at 2.4 million years ago^[2] or 5.3 million years ago.^[4]

The MYH16 gene is present in dogs,^[4] but does not appear to be present in mice.^[5]

External links

• Story from Science Scoop
• Hopkin M . Jaw-dropping theory of human evolution . Nature News . 25 March 2004 . 10.1038/news040322-9 .
• Web site: Symbol Report: MYH16 . HUGO Gene Nomenclature Committee (HGNC) .

Notes and References

1. Book: Carroll, Sean B. . Endless forms most beautiful: the new science of evo-devo and the making of the animal kingdom . Norton . New York . 2005 . 272–274 . 0-393-32779-5 .
2. Stedman HH, Kozyak BW, Nelson A, Thesier DM, Su LT, Low DW, Bridges CR, Shrager JB, Minugh-Purvis N, Mitchell MA . Myosin gene mutation correlates with anatomical changes in the human lineage . Nature . 428 . 6981 . 415–8 . March 2004 . 15042088 . 10.1038/nature02358 . 2004Natur.428..415S . 4304466 .
3. Pereira TV, Salzano FM, Mostowska A, Trzeciak WH, Ruiz-Linares A, Chies JA, Saavedra C, Nagamachi C, Hurtado AM, Hill K, Castro-de-Guerra D, Silva-Júnior WA, Bortolini MC . Natural selection and molecular evolution in primate PAX9 gene, a major determinant of tooth development . Proc. Natl. Acad. Sci. U.S.A. . 103 . 15 . 5676–81 . April 2006 . 16585527 . 1458632 . 10.1073/pnas.0509562103 . 2006PNAS..103.5676P . free .
4. Perry GH, Verrelli BC, Stone AC . Comparative analyses reveal a complex history of molecular evolution for human MYH16 . Mol. Biol. Evol. . 22 . 3 . 379–82 . March 2005 . 15470226 . 10.1093/molbev/msi004 . 44618003 . free .
5. Zhu J, Sanborn JZ, Diekhans M, Lowe CB, Pringle TH, Haussler D . Comparative genomics search for losses of long-established genes on the human lineage . PLOS Comput. Biol. . 3 . 12 . e247 . December 2007 . 18085818 . 2134963 . 10.1371/journal.pcbi.0030247 . 2007PLSCB...3..247Z . free .