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SIGLEC14 (sialic acid binding Ig-like lectin 14)

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Human Uniqueness Compared to "Great Apes": 
Absolute Difference
MOCA Domain: 
Genetics
MOCA Topic Authors: 
Ajit Varki

Siglec-14 is a sialic acid-recognizing activatory receptor found on certain immune cells types that is undergoing concerted evolution with the gene for Siglec-5 (an inhibitory receptor) via ongoing gene conversion of exons encoding amino-terminal V-set lg-like domains. The result is that the two molecules have similar binding properties for sialic acids. However surprisingly, a critical arginine residue required for sialic acid recognition has been mutated in the corresponding molecules from the chimpanzee, gorilla and orangutan. It appears that this may be the ancestral condition, and that the human molecules have restored the arginine residue required for sialic acid recognition. It is unclear what the evolutionary significance of this adjustment is, and further studies are needed.

 

Types of Human-Specific Changes in SIGLEC14:

Functional Differences in protein coding sequences

Partial Pseudogenization in the Human population

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TitleCertainty
SIGLEC5 (sialic acid binding Ig-like lectin 5 )True
Referenced By:
TitleCertainty
SIGLEC5 (sialic acid binding Ig-like lectin 5 )True
Timing

Timing of Appearance of the Difference in the Hominin Lineage.

For this entry assume that

  • the common ancestor of humans and old world monkeys was 25000 thousand (25 million) years ago
  • the common ancestor of humans and chimpanzees was 6000 thousand (6 million) years ago
  • the emergence of the genus Homo was 2000 thousand (2 million) years ago
  • the common ancestor of modern humans was 100 thousand years ago

 

Definite Appearance: 
100 Thousand Years
References: 

Angata, T., Hayakawa, T., Yamanaka, M., Varki, A., and Nakamura, M. 2006. Discovery of Siglec-14, a novel sialic acid receptor undergoing concerted evolution with Siglec-5 in primates. FASEB J. 20:1964-1973.
Carlin, A.F., Chang, Y.C., Areschoug, T., Lindahl, G., Hurtado-Ziola, N., King, C.C., Varki, A., and Nizet, V. 2009. Group B Streptococcus suppression of phagocyte functions by protein-mediated engagement of human Siglec-5. J Exp Med. 206:1691-1699.

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