D4-GDI (GDP dissociation inhibitor) is a negative regulator of the ras related Rho Family of GTPases. Since the rho GTPases promote cytoskeletal and membrane changes associated with apoptotic cell death, the removal of the D4-GDI block through its cleavage is important for inducing apoptosis. Caspase-3 cleaves the 28 kDa mature form of D4-GDI to give a 5 kDa and 23 kDa Size fragment. The 23 kDa fragment then translocates to the nucleus. The mechanisms involving cleavage of D4-GDI with apoptosis are not presently known. Activation of the Jun N-Terminal kinase, a regulator of apoptosis, may be one of the mechanisms.

Contributor: Sujay Singh and Peter Dias

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