Use of degenerate oligonucleotide primers and the polymerase chain reaction to clone gene family members.

As more and more genes are cloned and sequenced, it is apparent that nearly all genes are related to other genes. Similar genes are grouped into families. Examples of gene families include the collagen, globin, and myosin gene families. There are also gene superfamilies. Gene superfamilies are composed of genes that have areas of high homology and areas of high divergence. Examples of gene superfamilies include the oncogenes, homeotic genes, and a newly recognized gene superfamily of transmembrane proteins related to the lens fiber cells major intrinsic protein, or the MIP gene superfamily (1). In most cases, the different members of a gene family carry out related functions.