Characterization of a human import component of the mitochondrial outer membrane, TOMM70A.
Functional mitochondria require up to 1000 proteins to function properly, with 99% synthesized as precursors in the cytoplasm and transported into the mitochondria with the aid of cytosolic chaperones and mitochondrial translocators (import components). Proteins to be imported are chaperoned to the mitochondria by the cytosolic heat shock protein (cHSP70) and are immediately pursued by Translocators of the Outer Membrane (TOMs), followed by transient interactions of the unfolded proteins with Translocators of the Inner Membrane (TIMs). In the present study, we describe a human gene, TOMM70A, orthologous to the yeast Tom70 import component. TOMM70A is ubiquitously expressed in human tissues, maps on chromosome 3q13.1-q13.2 and consists of 12 coding exons spanning over 37 kb. TOMM70A localizes in the mitochondria of COS-7 cells, and in organello import assays confirmed its presence in the Outer Mitochondrial membrane (OM) of rat liver mitochondria. TOMM70A could play a significant role in the import of nuclear-encoded mitochondrial proteins with internal targeting sites such as ADP/ATP carriers and the uncoupling proteins.
Department of Medicine, Medical University of South Carolina, Charleston, SC 29403, USA.
Angela M
AM
Edmonson
Douglas K
DK
Mayfield
Virginie
V
Vervoort
Barbara R
BR
DuPont
George
G
Argyropoulos
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002893:Chromosomes, Human, Pair 3; D005656:Fungal Proteins; D006801:Humans; D006822:Hybrid Cells; D017404:In Situ Hybridization, Fluorescence; D007425:Intracellular Membranes / Q000378:metabolism*; D008565:Membrane Proteins; D026901:Membrane Transport Proteins / Q000096:biosynthesis* / Q000235:genetics*; D008930:Mitochondria, Liver / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011485:Protein Binding; D021381:Protein Transport; D011506:Proteins; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D005656:Fungal Proteins; C485725:KIAAO719 protein, rat; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; C402118:TOMM70 protein, human