Rings of RacGAP50C (red) and PBL (green) link spindle and furrow.

Saint/Elsevier

Once it gets going, cytokinesis is a simple squeeze. The complicated machinery is devoted instead to localizing the cytokinesis furrow. Now, Gregory Somers and Robert Saint (Australian National University, Canberra, Australia) have provided a link from mitotic spindle to contractile furrow that may explain how one positions the other.

The group started with the furrow-localized protein Pebble (PBL), a guanine nucleotide exchange factor (GEF) and thus activator for Rho1 and actin remodeling. Two-hybrid and coimmunoprecipitation experiments with PBL turned up RacGAP50C. The worm homologue of RacGAP50C, CYK-4, is essential for cytokinesis completion and binds a kinesin-like protein that bundles microtubules in the central spindle.

Consistent with these interactions, RacGAP50C was found in an inner ring near central spindle microtubules, abutting an outer ring of PBL. How these rings affect each other is unclear....

The Rockefeller University Press
2003
The Rockefeller University Press
2003
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