Maio et. al. presents a comprehensive and quantitative interactome of BZW2, a protein found to promote human cancers with little known about its molecular function. Many of the proteins identified were either mitochondrial or endoplasmic reticulum (ER) proteins, suggesting BZW2 may play a role in mitochondria-ER contact. We found that BZW2 indeed localizes to and promotes the formation of mitochondria-ER contact sites (MERCS), thus promoting calcium transport from ER to the mitochondria and promotes mitochondrial ATP production. These findings provide key insights into molecular functions of BZW2, the potential role of BZW2 in cancer progression, and highlights the utility of interactome data in understanding the function of less-studied proteins.