PLAC-24 is a cytoplasmic dynein-binding protein that is recruited to sites of cell-cell contact.
We screened for polypeptides that interact specifically with dynein and identified a novel 24-kDa protein (PLAC-24) that binds directly to dynein intermediate chain (DIC). PLAC-24 is not a dynactin subunit, and the binding of PLAC-24 to the dynein intermediate chain is independent of the association between dynein and dynactin. Immunocytochemistry using PLAC-24-specific polyclonal antibodies revealed a punctate perinuclear distribution of the polypeptide in fibroblasts and isolated epithelial cells. However, as epithelial cells in culture make contact with adjacent cells, PLAC-24 is specifically recruited to the cortex at sites of contact, where the protein colocalizes with components of the adherens junction. Disruption of the cellular cytoskeleton with latrunculin or nocodazole indicates that the localization of PLAC-24 to the cortex is dependent on intact actin filaments but not on microtubules. Overexpression of beta-catenin also leads to a loss of PLAC-24 from sites of cell-cell contact. On the basis of these data and the recent observation that cytoplasmic dynein is also localized to sites of cell-cell contact in epithelial cells, we propose that PLAC-24 is part of a multiprotein complex localized to sites of intercellular contact that may function to tether microtubule plus ends to the actin-rich cellular cortex.
Karki
Sher
S
Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104-6085, USA.
Ligon
Lee A
LA
DeSantis
Jamison
J
Tokito
Mariko
M
Holzbaur
Erika L F
EL
D022005:Adherens Junctions / Q000378:metabolism*; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D056445:Cytoplasmic Dyneins; D000072159:Dynactin Complex; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011485:Protein Binding; D051381:Rats
D000072159:Dynactin Complex; C468124:EIF3K protein, human; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; C486042:Dync1li1 protein, rat; D056445:Cytoplasmic Dyneins; D004398:Dyneins