THE POSSIBLE PRESENCE OF CAR2 GENE FAMILY IN SACCHAROMYCES-CEREVISIAEA364A

In early studies of ARSs in A364a chromosome V, 3 strains of A364a wit h ARS-containing plasmids which underwent recombination again after in sertion of foreign DNA from A364a chromosome V were isolated from the chromosome V-specific library. After extensive studies on the mechanis m of this recombination event, it was found that a common foreign DNA fragment (fragment A) of these 3 plasmids hybridized with A364a chromo some V, but not with E. coli genome DNA nor with yeast transposon elem ent Ty. This shows that fragment A originated from A364a chromosome V but not from other chromosome (since fragment A was isolated from plas mid out of chromosome V-specific library). Accidentally, the nucleotid e sequences of foreign DNAs inserted in pYA34 and pYA2 were highly hom ologous to that of CAR2 gene: 95% homologous to 5'-regulatory region, and 73.4% to the coding region. A possible explanation for this phenom enon was thus put forward: possible existence of CAR2 gene family in A 364 including inactive pseudogene and small fragmentary pieces of CAR2 gene. This is why these functionless pseudogenes and short fragmentar y pieces were not detected with the method based on their function by which CAR2 was assigned to chromosome XII.