Component of the TOM (translocase of outer membrane) complex; involved in recognition and initial import steps for all mitochondrially-directed proteins, acting as a receptor for incoming precursors; role in the distribution of tail-anchored proteins between mitochondria and peroxisomes; moonlighting role as a transcriptional regulator of mitochondrial proteins; age-dependent reduction in Tom70p results in mitochondrial dysfunction, a hallmark of aging; localizes to mitochondria–ER contact sites