The primary structure of rabbit liver cytosolic serine hydroxymethyltransferase

The complete amino acid sequence of cytosolic serine hydroxymethyltransferase from rabbit liver was determined. The sequence was determined from analysis of peptides isolated from tryptic and cyanogen bromide cleavages of the enzyme. Special procedures were used to isolate and sequence the C-terminal and blocked N-terminal peptides. Each of the four identical subunits of the enzyme consists of 483 residues. The sequence could be easily aligned with the sequence of Escherichia coli serine hydroxymethyltransferase. The primary structural homology between the rabbit and E. coli enzymes is about 42%. The importance of the primary and predicted secondary structural homology between the two enzymes is discussed.