The Conserved Gene and Its Alleles
Thy-1 has been conserved throughout vertebrate evolution and even in some invertebrates, with homologs described in many species like squid, frogs, chickens, mice, rats, dogs, and humans.
The Thy-1 gene is located at human chromosome 11q22.3 (mouse chromosome 9qA5.1). Some believe that there may be a functional significance of both this gene and CD3 delta subunit (T3D) mapping to chromosome 11q in man and chromosome 9 in mouse, though there is no homology (in fact this speculation lead to its localization in chromosome 11q - the human chromosome region syntenic to mouse chromosome 9 which harbored T3D). In mice, there are two alleles: Thy1.1 (Thy 1a, CD90.1) and Thy1.2 (Thy 1b, CD90.2). They differ by only one amino acid at position 108; an arginine in Thy-1.1 and a glutamine in Thy-1.2. Thy 1.2 is expressed by most strains of mice, whereas Thy1.1 is expressed by some like AKR/J and PL mouse strains.
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