Genes and gene families - Human Gene Evolution - page 143

http://flybase.bio.indiana.edu/ ). Examples (with human chromosomal locations
where known) include proto-oncogenes jun ( JUN ; 1p31-p32; Perkins et al ., 1988)
and fos ( FOS ; 14q24; Perkins et al ., 1988), flightless I ( FLI1 ; 17p11.2; Campbell et
al ., 1997), minibrain ( MNBH ; 21q22.2; Guimera et al ., 1996), dorsal ( REL ; 2p12-
p13; Steward 1987), atonal ( ATOH1 ; 4q22; Ben-Arie et al ., 1996), archain
( ARCN1 ; 11q23; Radice et al ., 1995), tumor suppressor gene lethal 2 giant larvae
( LLGL1 ; 17p11-p12; Strand et al ., 1995), transient receptor potential channel-
related protein 1 ( TRPC1 ; Wes et al ., 1995), succinate dehydrogenase, iron-sul-
fur protein subunit ( SDH1 ; 1p22.1-qter; Au and Scheffler 1994), slowpoke ( SLO ,
chromosome 10; Pallanck and Ganetzky 1994), enhancer of split ( TLE1 ; 19p13.3;
Stifani et al ., 1992), dodo ( PIN1 , Maleszka et al ., 1996), EGF receptor ( EGFR ;
7p12.1-p12.3; Livneh et al ., 1985), dishevelled ( DVL1 ; 1p36; Pizzuti et al ., 1996),
son of sevenless ( SOS1, 2p21-p22; SOS2 , 14q21; Della et al ., 1995), awd ( NME1
(17q21.3; Zinyk et al ., 1993), Ddx1 DEAD box polypeptide ( DDX1 ; 2p24; Rafti
et al ., 1996), cut ( CUTL ; 7q22; Neufeld et al ., 1992), and the paired box domain
family of transcription factors that play an important role in development
( PAX1 , 20p11.2; PAX2 , 10q25; PAX3 , 2q36; PAX4 , 7q22-qter; PAX5 , 9p13;
PAX6 , 11p13; PAX7 , 1p36; PAX8 , 2q12-q14; PAX9 , 14q12-q14; Quiring et al .,
1994; Balczarek et al ., 1997; Czerny et al ., 1997).
Homologs of the ETS1 proto-oncogene, located on human chromosome
11q23, have been found not only in Drosophila (Laudet et al ., 1993) but through-
out the metazoa in organisms as evolutionarily distant as sponges, anenomes,
flatworms and nematodes (Degnan et al ., 1993; Laudet et al ., 1999). The origin
of the ETS genes therefore appears to predate the divergence of the schizocoeles
(arthropods, annelids etc) from the pseudocoeles (nematodes) more than 750
Myrs ago (Doolittle et al ., 1996). STAT (Signal Transducers and Activators of
Transcription) proteins represent an example of proteins present in Drosophila
and Dictyostelium but not in yeast (Kawata et al ., 1997) and so must have
emerged at some stage during the adaptive radiation of the metazoa. Homology
is also evident between members of the human lipase gene family [lipoprotein
lipase ( LPL ; 8p22), hepatic lipase ( LIPC ; 15q21-q23) and pancreatic lipase
( PNLIP ; 10q26)] and the yolk proteins of Drosophila (Hide et al ., 1992;
Kirchgessner et al ., 1989).
Another example of a gene with an ancestry stretching back at least as far as
750 Myrs, is a human retina-expressed gene, CAGR1 (13q13) which is homolo-
gous to the Caenorhabditis elegans cell fate-determining gene, mab -21 (Margolis
et al ., 1996). Ahringer (1997) presented evidence that at least 50% of
Caenorhabditis genes are likely to have counterparts in the human genome.
Similarly, the human neurotrophic tyrosine kinase receptor ( NTRK3 ; 15q25)
gene has a homologue in the snail, Lymnea stagnalis (van Kesteren et al ., 1998)
although not apparently in C. elegans .
Ancient conserved regions , deemed to be regions of the greatest structural or func-
tional importance on account of their evolutionary conservation are also evident
in various other proteins with homologues in both human and C. elegans , for
example adenylate cyclases, epidermal growth factor-like domains, gelsolin, inter-
mediate filament proteins, kinesins, neurotransmitter transporters and the ubiq-
uitins (Green et al ., 1993).