C. Popovici et al., The family of Caenorhabditis elegans tyrosine kinase receptors: Similarities and differences with mammalian receptors, GENOME RES, 9(11), 1999, pp. 1026-1039
Transmembrane receptors with tyrosine kinase activity (RTK) constitute a su
perfamily of proteins present in all metazoans that is associated with the
control and regulation of cellular processes. They have been the focus of n
umerous studies and are a good subject for comparative analyses of multigen
e families in different species aimed at understanding metazoan evolution.
The sequence of the genome of the nematode worm Caenorhabditis elegans is a
vailable. This offers a good opportunity to study the superfamily of nemato
de RTKs in its entirety and to compare it with its mammalian counterpart. W
e show that the C. elegans RTKs constitute various groups with different ph
ylogenetic relationships with mammalian RTKs. A group of four RTKs show str
uctural similarity with the three mammalian receptors For the vascular endo
thelial growth Factors. Another group comprises RTKs with a short extracell
ular region, a feature not known in mammals; the genes encoding these RTKs
are clustered on chromosome II with other gene families, including genes en
coding chitinase-like proteins. Most of the C. elegans RTKs have no direct
orthologous relationship with any mammalian RTK, providing an illustration
of the importance of the separate evolution of the different phyla.