The dispersed, repeated family of MAL loci in Saccharomyces spp.

This report concludes our analysis of the various standard maltose-fermenting strains of Saccharomyces spp. We showed that, in addition to either the MAL2 or MAL4 functional locus present in the standard MAL2 and MAL4 strains, both strains contain two cryptic MALg genes mapping to the MAL1 and MAL3 locus positions. (Functional MAL loci appear to consist of two linked complementing gene functions, MALp and MALg. Cryptic MALg genes lack a linked functional MALp gene.) Using a probe containing a DNA fragment derived from the MAL6 locus, we detected three genomic HindIII fragments in both the MAL2 and MAL4 strains. Each of these HindIII fragments is shown to segregate in a Mendelian fashion and to be linked to one of the three MAL loci in each of the strains. We also detected additional fragments having significant sequence homology to the MAL6 probe but lacking in MAL-related functions.