Characterization of Three cDNAs Encoding Two Isozymes of an Isoaspartyl Protein Carboxyl Methyltransferase from Human Erythroid Leukemia Cells

抄録

Two different sizes (approximately 1.0 and 1.6 kb) of transcripts of an isoaspartyl protein carboxyl methyltransferase (PIMT) were detected in eight cell lines derived from human hemopoietic cells on Northern blot analysis. We found three different sizes of cDNAs (907, 1, 553, and 1, 600 bp) in human erythroid leukemia cells (HEL) and a unique cDNA sequence corresponding to the 1.0 kb transcript was identified. These three cDNA sequences encoded two isozymes consisting of 226 (isozyme I) and 227 (isozyme II) amino acids. The 1.6 kb transcript was translated into two isozymes (isozyme I and II), while the 1.0 kb transcript was only translated into isozyme I. These results suggest that the two isozymes deduced from the cDNAs of the human erythroid leukemia cells may exist in normal human erythrocytes.