THE ROLE OF MICROTUBULE-BASED MOTOR PROTEINS IN MAINTAINING THE STRUCTURE AND FUNCTION OF THE GOLGI-COMPLEX

The intimate association between the Golgi complex and the microtubule cytoskeleton plays an important role in Golgi structure and function. Recent evidence indicates that the dynamic flow of material from the ER to the Golgi is crucial to maintaining the integrity of the Golgi c omplex and its characteristic location within the cell, and it is now clear that this flow is dependent on the ongoing activity of microtubu le motor proteins. This review focuses primarily on recent microinject ion and expression studies which have explored the role of individual microtubule motor proteins in controlling Golgi dynamics. The collecti ve evidence shows that one or more isoforms of cytoplasmic dynein, tog ether with its cofactor the dynactin complex, are required to maintain a juxtanuclear Golgi complex in fibroblasts. Although questions remai n about how dynein and dynactin are linked to the Golgi, there is evid ence that the Golgi-spectrin lattice is involved. Kinesin and kinesin- like proteins appear to play a smaller role in Golgi dynamics, though this may be very cell-type specific. Moreover, new evidence about the role of kinesin family members continues to emerge. Thanks in part to recent advances in our understanding of these molecular motors, our cu rrent view of the Golgi complex is of an organelle in flux, undergoing constant renewal. Future research will be aimed at elucidating how an d to what extent these motor proteins function as regulators of Golgi function. (C) 1998 Elsevier Science B.V. All rights reserved.