Human.

A novel Bax-associating protein, named MAP-1 (Modulator of Apoptosis), mediates caspase-dependent apoptosis in mammalian cells when overexpressed. MAP-1 homodimerizes and associates with the proapoptotic Bax and the prosurvival Bcl-2 and Bcl-X(L) of the Bcl-2 family in vitro and in vivo in mammalian cells. These data suggest that MAP-1 mediates apoptosis through a mechanism that involves binding to Bax.

Apoptosis plays a major role in normal organism development, tissue homeostasis, and removal of damaged cells. Disruption of this process has been implicated in a variety of diseases such as cancer. Members of the Bcl-2 family are known to be critical regulators of this process. These proteins are characterized by the presence of several conserved motifs termed Bcl-2 homology (BH) domains. A related protein termed MAP-1 has recently been identified. This protein contains a BH3-like domain and induces caspase-dependent apoptosis in mammalian cells when overexpressed. It forms homodimers and associates with Bcl-2 family members such as Bax, Bcl-2, and Bcl-XL in vitro and in vivo. It has been suggested that MAP-1 associates with the tumor suppressor RASSF1A following death receptor activation, allowing a conformational change in Bax that leads to cellular apoptosis.