AMINO-ACID SEQUENCING, MOLECULAR-CLONING AND MODELING OF THE CHICK LIVER CLASS-THETA GLUTATHIONE-S-TRANSFERASE CL1

Glutathione S-transferase CL1-2 heterodimers purified from 1-day-old chick livers were digested with Achromobacter proteinase I. The resulting fragments were separated for amino acid sequence analysis. Oligonucleotide; probes were constructed based on sequence similarity to class-Theta glutathione S-transferases for PCR using chicken liver cDNA library as template. A full-length clone (1725 bp) encoding a polypeptide comprising 261 amino acids was isolated. Including conservative substitutions,this protein has 70-73% sequence similarity with other mammalian class-Theta gluthathione S-transferases. Based on known X-ray crystal structures of class-Alpha, -Mu and -Pi glutathione S-transferases, a model is constructed for the N-terminal 232 residues of CL1.