THE CDNA-ENCODING CANINE DIHYDROLIPOAMIDE DEHYDROGENASE CONTAINS MULTIPLE TERMINATION SIGNALS

A 2288-bp cDNA sequence encoding dihydrolipoamide dehydrogenase (DLDH; dihydrolipoamide: NAD(+) oxidoreductase; EC 1.8.1.4) was obtained by isolating a 1762-bp cDNA clone from a canine skeletal muscle library i n the vector, lambda UNIZAP, combined with PCR amplification of the 5' end of the mRNA, The DLDH cDNA sequence contains a 49-bp G + C-rich 5 '-untranslated region (UTR), followed by 1527 bp of coding region, and 695 bp of 3'-UTR preceding a 17-bp poly(A) tail. The single open read ing frame encodes a precursor DLDH of 509 amino acids (aa) that begins with a 35-aa leader sequence, The 3'-UTR includes six possible polyad enylation signals (three AATAAA, one TATAAA and two AATGAA) and one po tential stem-loop region extending from bp 1969-1991. Alignment studie s of the canine and human DLDH demonstrate homology within the coding region of 98% at the aa level and 94% at the nt level. Northern blot a nalysis using the cDNA clone as probe showed wide tissue distribution of the mRNA, with differences in the level of expression among tissues and possible utilization of different polyadenylation sites.