GOLGI SPECTRIN - IDENTIFICATION OF AN ERYTHROID BETA-SPECTRIN HOMOLOGASSOCIATED WITH THE GOLGI-COMPLEX

Spectrin is a major component of a membrane-associated cytoskeleton in volved in the maintenance of membrane structural integrity and the gen eration of functionally distinct membrane protein domains. Here, we sh ow that a homolog of erythrocyte beta-spectrin (beta I Sigma) co-loca lizes with markers of the Golgi complex in a variety of cell types, an d that microinjected beta-spectrin codistributes with elements of the Golgi complex. Significantly, we show a dynamic relationship between b eta-spectrin and the structural and functional organization of the Gol gi complex. Disruption of both Golgi structure and function, either in mitotic cells or following addition of brefeldin A, is accompanied by loss of beta-spectrin from Golgi membranes and dispersal in the cytop lasm. In contrast, perturbation of Golgi structure without a loss of f unction, by the addition of nocodazole, results in retention of beta-s pectrin with the dispersed Golgi elements. These results indicate that the association of beta-spectrin with Golgi membranes is coupled to G olgi organization and function.