Centrosomal dynactin is required for normal microtubule anchoring and/or focusing independently of dynein. Dynactin is present at centrosomes throughout interphase, but dynein accumulates only during S and G2 phases. Blocking dynein-based motility prevents recruitment of dynactin and dynein to centrosomes and destabilizes both centrosomes and the microtubule array, interfering with cell cycle p...

Cytoplasmic dynein-1 binds dynactin and cargo adaptor proteins to form a transport machine capable of long-distance processive movement along microtubules. However, it is unclear why dynein-1 moves poorly on its own or how it is activated by dynactin. Here, we present a cryoelectron microscopy structure of the complete 1.4-megadalton human dynein-1 complex in an inhibited state known as the phi...

Variations in subunit composition and modification have been proposed to regulate the multiple functions of cytoplasmic dynein. Here, we examine the role of the Drosophila ortholog of tctex-1, the 14-kDa dynein light chain. We show that the 14-kDa light chain is a bona fide component of Drosophila cytoplasmic dynein and use P element excision to generate flies that completely lack this dynein s...

Most cellular organelles are posi­ tioned through active transport by motor proteins. this is espe­ cially important during cell division, a time when the organelles and genetic content need to be divided equally between the two daughter cells. although individual proteins can attain their correct location by diffusion, larger structures are usually posi­ tioned through active transport by moto...

Nuclei are precisely positioned within all cells, and mispositioned nuclei are a hallmark of many muscle diseases. Myonuclear positioning is dependent on Kinesin and Dynein, but interactions between these motor proteins and their mechanisms of action are unclear. We find that in developing Drosophila muscles, Dynein and Kinesin work together to move nuclei in a single direction by two separate ...

Microtubules undergo alternating periods of growth and shortening, known as dynamic instability. These dynamics allow microtubule plus ends to explore cellular space. The "search and capture" model posits that selective anchoring of microtubule plus ends at the cell cortex may contribute to cell polarization, spindle orientation, or targeted trafficking to specific cellular domains. Whereas cyt...

The centrosome is the major microtubule-organizing center in animal cells. Although the cytoplasmic dynein regulator Nudel interacts with centrosomes, its role herein remains unclear. Here, we show that in Cos7 cells Nudel is a mother centriole protein with rapid turnover independent of dynein activity. During centriole duplication, Nudel targets to the new mother centriole later than ninein bu...

During mitosis in Saccharomyces cerevisiae, the mitotic spindle moves into the mother-bud neck via dynein-dependent sliding of cytoplasmic microtubules along the cortex of the bud. Here we show that Pac1, the yeast homologue of the human lissencephaly protein LIS1, plays a key role in this process. First, genetic interactions placed Pac1 in the dynein/dynactin pathway. Second, cells lacking Pac...

Chlamydomonas 12 S dynein, which makes up part of the outer arm of the flagellar axoneme, consists of three polypeptides of 330,000, 22,000, and 18,000 daltons. We have used 8-azidoadenosine 5'-triphosphate (8-N3ATP), a photoaffinity analog of ATP, to investigate which of the dynein polypeptides contains the site of ATP hydrolysis. 8-N3ATP is a competitive inhibitor of the hydrolysis of ATP by ...

Neurodegenerative disease in humans and mice can be caused by mutations affecting the microtubule motor dynein or its biochemical regulator, dynactin, a multiprotein complex required for dynein function (1-4). A single amino acid change, G59S, in the conserved cytoskeletal-associated protein glycine-rich (CAP-Gly) domain of the p150(glued) subunit of dynactin can cause motor neuron degeneration...