Sialoadhesin on Macrophages

Certainty Style Key

Certainty styling is being phased out topic by topic.

Hover over keys for definitions:
True   Likely   Speculative
Human Uniqueness Compared to "Great Apes": 
Likely Difference
MOCA Domain: 
MOCA Topic Authors: 

Siaoloadhesin (Sn, Siglec-1) is a sialic acid binding cell surface receptor of as yet unknown function that is found on subsets of macrophages in the lymphoid system and the bone marrow. The sialic acid-binding preference of this receptor favors Neu5Ac, the type of sialic acid found in excess on human cell surfaces, because of the genetic loss of the great ape sialic acid Neu5Gc. Human cells therefore have an excess of binding sites for this receptor. Possibly in relation to this difference, the distribution of Sn in human macrophages appears different between humans and chimpanzees. The chimpanzee pattern is similar to that of the rat, with only a subset being positive, and with negative areas in the center of the splenic follicles. In contrast human spleen macrophages appear to be almost universally positive for Sn, including within the follicles. 


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

Possible Appearance: 
3,000 thousand years ago
Definite Appearance: 
100 thousand years ago


No related publications have been added for this topic