Stimulation of the Synthesis of Fructose 1,6-Diphosphate Aldolase by Transferrin

Abstract

The glycolytic enzyme aldolase (E.C.4.1.2.13) catalyzes the reversible cleavage of fructose 1,6-diphosphate to yield dihydorxyacetone phosphate and D-glyceraldehyde 3-phosphate. During embryonic development in skeletal muscle, this tetrameric enzyme undergoes a transition from a macromolecule composed primarily of C subunits to a homotetramer composed of A subunits (332–334). The work of Lebherz has shown that the steady-state concentration of aldolase and other glycolytic enzymes in “fast” and “slow-twitch” skeletal muscle fibers is regulated almost solely at the level of protein synthesis (334,335). During post-embryonic development, the synthetic rate of aldolase becomes four-fold faster in “fast-twitch” chicken breast muscle as compared to “slow-twitch” leg muscle (334–336). Thus, in terms of the glycolytic enzymes, fiber-type differentiation appears to progress via a transformation from a slow-type phenotype to a fast-type (335).

The authors wish to express their thanks to Dr. D. Hoover, Mr. G. Holm, Mrs. J.L. Johnson and Mrs. F.F. Spaven for technical assistance and to Mrs. E. DeLong for editorial help. This work was supported by grants from the NIH (NS 16076-G.J.M. and NS 15013-THO), the MDA (T.H.).) and the Frank C. Bressler Research Fund of the University of Maryland (G.J.M.).