GLRA4 (Glycine receptor, alpha 4)

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Human Uniqueness Compared to "Great Apes": 
Likely Difference
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The glycine receptor alpha 4 (GLRA4) is a human lineage specific processed pseudogene. Glycine receptors are membrane bound ligand-gated chloride channels mediated by glycine, which acts as an inhibitory neurotransmitter. Glycine receptors are pentameric channels composed of four alpha subunits and one beta subunit. Most mammals have 4 functional alpha subunit genes, however, in humans alpha 4 is a pseudogene. Implications for the loss of function of GLRA4 is unknown.


Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. The point in time associated with lineage separation events may change in the future as the scientific community agrees upon better time estimates. Lineage separation events are defined in 2017 as:

  • the Last Common Ancestor (LCA) of humans and old world monkeys was 25,000 - 30,000 thousand (25 - 30 million) years ago
  • the Last Common Ancestor (LCA) of humans and chimpanzees was 6,000 - 8,000 thousand (6 - 8 million) years ago
  • the emergence of the genus Homo was 2,000 thousand (2 million) years ago
  • the Last Common Ancestor (LCA) of humans and neanderthals was 500 thousand years ago
  • the common ancestor of modern humans was 100 - 300 thousand years ago

Definite Appearance: 
6,000 thousand years ago
Genetics Topic Attributes
Gene symbols follow the HUGO Gene Nomenclature Committee standard.
Gene Symbol Type of Human-Specific Changes
GLRA4 Pseudogenization


  1. Novel expression of a functional glycine receptor chloride channel that attenuates contraction in airway smooth muscle., Yim, Peter D., Gallos George, Xu Dingbang, Zhang Yi, and Emala Charles W. , FASEB J, 05/2011, Volume 25, Issue 5, p.1706-17, (2011)
  2. Divergence, demography and gene loss along the human lineage., Kim, Hie Lim, Igawa Takeshi, Kawashima Ayaka, Satta Yoko, and Takahata Naoyuki , Philos Trans R Soc Lond B Biol Sci, 2010 Aug 27, Volume 365, Issue 1552, p.2451-7, (2010)
  3. Molecular structure and function of the glycine receptor chloride channel., Lynch, J. W. , Physiol Rev, 10/2004, Volume 84, Issue 4, p.1051-95, (2004)