The acid phosphatase genes PHO10 and PHO11 in S. cerevisiae are located at the telomeres of chromosomes VIII and I.

Of the three regulated acid phosphatase genes in S. cerevisiae (PHO5, PHO10 and PHO11) two have previously been cloned (PHO5 and PHO11). We have now identified PHO10 and show by restriction mapping that it is highly homologous to PHO11. This homology includes not only the coding sequence but also a stretch of about 2 kb upstream and 2.2 kb downstream of the genes. Analysis of strains in which either gene had been disrupted shows that the two genes are located at the telomeres of two different chromosomes. PHO10 3.6 kb from the end of a chromosome I. This makes PHO11 the gene closest to the end of a chromosome that has been physically mapped so far in S. cerevisiae. The organization of the two genes varies strongly from strain to strain consistent with a high incidence of telomere rearrangement. In one of twenty transformants examined a conversion event could be directly demonstrated that resulted in a chromosome VIII which had acquired a copy of the telomere from chromosome I.