Molecular characterization of the 50-kD subunit of dynactin reveals function for the complex in chromosome alignment and spindle organization during mitosis.

• DOI: 10.1083/jcb.132.4.617
• Publication Date: 2004-05-15T01:23:47Z
• Authors: C J Echeverri; B M Paschal; K T Vaughan; R B Vallee
• Keywords: Dynactin; Prometaphase

Dynactin is a multi-subunit complex which has been implicated in cytoplasmic dynein function, though its mechanism of action unknown. In this study, we have characterized the 50-kD subunit dynactin, and analyzed effects overexpression on mitosis living cells. Rat human cDNA clones revealed p50 to be novel highly conserved, containing three predicted coiled-coil domains. Immunofluorescence staining dynactin components cultured vertebrate cells showed that both complexes are recruited kinetochores during prometaphase, concentrate near spindle poles thereafter. Overexpression COS-7 disrupted mitosis, causing accumulate prometaphase-like state. Chromosomes were condensed but unaligned, spindles, while still bipolar, dramatically distorted. Sedimentation analysis dissociated transfected cultures. Furthermore, at prometaphase was markedly diminished expressing high levels p50. These findings represent clear evidence for codistribution within cells, presence kinetochores. The data also provide direct vivo role modulating binding an organelle, implicate chromosome alignment organization.