Cell
Volume 74, Issue 4, 27 August 1993, Pages 609-619
Journal home page for Cell

Article
Bcl-2 heterodimerizes in vivo with a conserved homolog, Bax, that accelerates programed cell death

https://doi.org/10.1016/0092-8674(93)90509-OGet rights and content

Abstract

Bcl-2 protein is able to repress a number of apoptotic death programs. To investigate the mechanism of Bcl-2's effect, we examined whether Bcl-2 interacted with other proteins. We identified an associated 21 kd protein partner, Bax, that has extensive amino acid homology with Bcl-2, focused within highly conserved domains I and II. Bax is encoded by six exons and demonstrates a complex pattern of alternative RNA splicing that predicts a 21 kd membrane (α) and two forms of cytosolic protein (β and γ). Bax homodimerizes and forms heterodimers with Bcl-2 in vivo. Overexpressed Bax accelerates apoptotic death induced by cytokine deprivation in an IL-3-dependent cell line. Overexpressed Bax also counters the death repressor activity of Bcl-2. These data suggest a model in which the ratio of Bcl-2 to Bax determines survival or death following an apoptotic stimulus.

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