IDENTIFICATION OF NEURONAL ISOZYME SPECIFIC RESIDUES BY COMPARISON OFGOLDFISH ALDOLASE-C TO OTHER ALDOLASES

A 2061 bp cDNA encoding a goldfish (Carassius auratus) aldolase was is olated from a goldfish brain library. The deduced 362 amino acid seque nce is more similar to vertebrate brain (aldolase C) and muscle aldola ses (aldolase A) than to the liver isozymes (aldolase B). Northern blo t analysis indicates strong expression of the mRNA in brain but not in liver or muscle, which indicates that this is aldolase C rather than aldolase A. Analysis of all known vertebrate aldolase amino acid seque nces reveals five residues; Leu-57, Arg-314, Thr-324, Glu-332, and Gly -350 that are present exclusively in aldolase Cs. The goldfish clone p ossesses air five residues. The residues are primarily located in the carboxyl-terminal region of the enzyme and may play a role in determin ing the neuronal isozyme-specific properties of the enzyme. Furthermor e, the existence of an aldolase C in a teleost fish has implications w ith respect to the timing of genome duplication events that are though t to have been critical in vertebrate evolution. (C) 1997 Elsevier Sci ence Inc.