Localization of Tctex-1, a Cytoplasmic Dynein Light Chain, to the Golgi Apparatus and Evidence for Dynein Complex Heterogeneity

Abstract

To date, much attention has been focused on the heavy and intermediate chains of the multisubunit cytoplasmic dynein complex; however, little is known about the localization or function of dynein light chains. In this study, we find that Tctex-1, a light chain of cytoplasmic dynein, localizes predominantly to the Golgi apparatus in interphase fibroblasts. Immunofluorescent staining reveals striking juxtanuclear staining characteristic of the Golgi apparatus as well as nuclear envelope and punctate cytoplasmic staining that often decorates microtubules. Tctex-1 colocalization with Golgi compartment markers, its distribution upon treatment with various pharmacological agents, and the cofractionation of Tctex-1-associated membranes with Golgi membranes are all consistent with a Golgi localization. The distribution of Tctex-1 in interphase cells only partially overlaps with the dynein intermediate chain and p150Glued upon immunofluorescence, but most of Tctex-1 is redistributed onto mitotic spindles along with other dynein/dynactin subunits. Using sequential immunoprecipitations, we demonstrate that there is a subset of Tctex-1 not associated with the intermediate chain at steady state; the converse also appears to be true. Distinct populations of dynein complexes are likely to exist, and such diversity may occur in part at the level of their light chain compositions.

Immunogold method evidences that kinesin and myosin bind to and couple microtubules and actin filaments in lipotubuloids of Ornithogalum umbellatum ovary epidermis

“…They are core elements of eukaryotic cells probably binding with hundreds of proteins (Rapali et al 2011). The presence of dynein light chain molecules in fibroblast Golgi structures (Tai et al 1998) support our observations reaviling them by immunogold method as gold grains in lipotubuloid Golgi structures. Other authors believe that Golgi structure movements depend on myosin XI (Avisar et al 2009(Avisar et al , 2012.…”

Structural and thermodynamic characterization of a cytoplasmic dynein light chain–intermediate chain complex

“…Based on our data of the monomeric nNOS peptide, which indicate that this peptide binds with higher affinity than the monomeric IC, a dimeric analog of nNOS peptide should have higher affinity. Furthermore, it is estimated that the majority of the LCs are not associated with dynein (40,41). These estimates suggest that interaction of the LCs with the ICs represents a subset of LC targets.…”

Phosphorylation by cdc2-CyclinB1 Kinase Releases Cytoplasmic Dynein from Membranes

“…One interesting question is whether the regulatory mechanism we have characterized operates during mitosis in somatic cells (rather than through the embryonic cell cycle, as assessed here and previously), as there are conflicting reports of whether CD remains associated with its membranous cargoes (43,44).…”

“…9 for a review) that have to be stimulated on entry into mitosis, such as the interaction with NuMA (45) and those like the interaction between LIC1 and pericentrin, which may be active at all times (46,47). To add to this complexity, there may be distinct CD complexes that contain specific assortments of subunits, which may be responsible for different CD functions (44,47) and which could be differentially regulated. Other microtubule motors, such as Eg5 and MKLP1, may also be regulated by cdc2 kinase and other cell cycle-regulated kinases (48 -51).…”