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Ralph M Bernstein ralph at ccit.arizona.edu
Sat Jan 21 17:59:44 EST 1995

In article <3fneba$m73 at decaxp.harvard.edu>
robison at lipid.harvard.edu (Keith Robison) writes:
>Ram Samudrala (ram at mbisgi.umd.edu) wrote:
>: I'd like to know if there's a database or listing of families of genes
>: that occur in a single DNA molecule (a single chromosome or plasmid).

>There's no shortage of what you are looking for. [...]
>Vertebrate immunoglobulin genes are arrayed in large clusters,
>and many of these have been sequenced (or in a similar vein, 
>large stretches of the human T-cell receptor loci have been
>completely sequenced).  Homeobox genes are another example of
>local duplications.
    And it gets even better than this, the entire Ig superfamily (which not
only includes TCRs, but antibodies, MHC, the Icams, the Ncams, Thy 1, ect,
ect) is probably made up of one duplicated gene segment, a small Ig domain
that is reproduced in many different genes and usually seen multiple times
in each gene -not just in ALL  vertebrates,(all jawed vertebrates have been
shown to have Ig) but also in more "primative" organisms including moths, ect.  
    This type of duplication, although not as overwhelmingly prevelant as in
the Ig genes, is also seen in many adhesion moleclues, eg integrins, and in
some receptor families, eg FSH, LH receptors.  

Ralph M. Bernstein
Dept of Micro/Immuno
University of Arizona
Ph: 602 626 2585
Fx: 602 626 2100

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