GLYCOLYTIC-ENZYMES AND ASSEMBLY OF MICROTUBULE NETWORKS

The ability of glycolytic enzymes, glyceraldehyde-3-phosphate dehydrog enase (GAPDH), aldolase, pyruvate kinase (PK), and lactate dehydrogena se muscle-type (LDH(M)), to generate interactive microtubule networks was investigated, Bundles have previously been defined as the parallel alignment of several microtubules and are one form of microtubule net works, Utilizing transmission electron microscopy, interactive network s of microtubules as well as bundles were readily observed in the pres ence of GAPDH, aldolase, or PK, These networks appear morphologically as cross-linked microtubules, oriented in many different ways, Light s cattering indicated that the muscle forms of GAPDH, aldolase, PK, and LDH(m) caused formation of the microtubule networks, Triose phosphate isomerase (TPI) and lactate dehydrogenase heart-type (LDH(H)), glycoly tic enzymes which do not interact with tubulin or microtubules, did no t produce bundles, or interactive networks, Sedimentation experiments confirmed that the enzymes that cross-link also co-pellet with the mic rotubules, Such cross-linking of microtubules indicate that the enzyme s are multivalent with the capability of simultaneous binding to more than one microtubule.