Identification of genes from pattern formation, tyrosine kinase, and potassium channel families by DNA amplification.

The study of gene family members has been aided by the isolation of related genes on the basis of DNA homology. We have adapted the polymerase chain reaction to screen animal genomes very rapidly and reliably for likely gene family members. Using conserved amino acid sequences to design degenerate oligonucleotide primers, we have shown that the genome of the nematode Caenorhabditis elegans contains sequences homologous to many Drosophila genes involved in pattern formation, including the segment polarity gene wingless (vertebrate int-1), and homeobox sequences characteristic of the Antennapedia, engrailed, and paired families. In addition, we have used this method to show that C. elegans contains at least five different sequences homologous to genes in the tyrosine kinase family. Lastly, we have isolated six potassium channel sequences from humans, a result that validates the utility of the method with large genomes and suggests that human potassium channel gene diversity may be extensive.