Isozymes and the micro-organization of the glycolytic sequence.

A study of the ontogenic characteristics of glycolytic enzymes in mammalian tissues has demonstrated an extensive degree of association between these enzymic components and cellular structure in all tissues during development. Furthermore, these associations tended to be highly isozyme specific. In reviewing these data, a model has been developed which describes the novel features of this compartmentation-by-binding. The glycolytic sequence in vivo is depicted as a number of segments, each formed by a cluster of isozymes, many of which can interact with the actin-containing filaments of the cytomatrix. Evidence is provided that this form of compartmentation plays a key role in meeting the different types of energy requirement in the cytoplasm, with the wide selection of isozymes in this system providing increased flexibility and control in this important area of metabolism.