ISOLATION AND EXPRESSION OF A RAT-LIVER CDNA-ENCODING PHOSPHOGLUCOMUTASE

A cDNA encoding phosphoglucomutase (PGM) has been isolated from a rat liver cDNA library following screening with a polymerase chain reactio n product. The cDNA was found to contain a 53-base-pair (bp) 5' untran slated region (5' UTR), a single start codon and consensus initiation sequence, an open reading frame (ORF) of 1686 bp, and a 3' untranslate d tail. A comparison to the rabbit and human muscle PGM cDNAs [Whiteho use et al., Proc. Natl. Acad. Sci. USA 89 (1992) 411-415] showed 90% i dentity of rat cDNA to both, while a comparison to the deduced amino a cid sequences showed 97 and 96% identity, respectively. Northern blot analyses determined that PGM was encoded by a single mRNA in rat liver , of approximately 2.2 kb. Following transfection of COS-7 cells with a plasmid containing the entire PGM ORF, indirect immunofluorescence a nalyses using a PGM-specific monoclonal antibody determined that appro ximately 5% of the cells displayed 50-100 times greater fluorescence t han that seen in the remainder of the cells or in mock transfects. The enhanced production of PGM was also demonstrated by Western blotting and by enzymatic activity assays.