Cell Biology

Cell Biology T. Sollner, G. Griffiths, R. Pfaller, N. Pfanner, W. Neupert, "MOM19, an import receptor for mitochondrial precursor proteins," Cell, 59:1061-70, 1989. Thomas Sollner (University of Munich): "The complex organization of eucaryotic cells into various membrane-bound compartments (organelles) requires a very specific targeting of newly synthesized proteins to their final destinations. All noncytosolic proteins are synthesized as signal-carrying precursors, which are decode

Oct 14, 1991
The Scientist Staff

Cell Biology


T. Sollner, G. Griffiths, R. Pfaller, N. Pfanner, W. Neupert, "MOM19, an import receptor for mitochondrial precursor proteins," Cell, 59:1061-70, 1989.

Thomas Sollner (University of Munich): "The complex organization of eucaryotic cells into various membrane-bound compartments (organelles) requires a very specific targeting of newly synthesized proteins to their final destinations. All noncytosolic proteins are synthesized as signal-carrying precursors, which are decoded by receptor-like structures on the surface of the organelles. In the cited article, we describe the identification of MOM19, a 19-kilodalton protein. This is the first mitochondrial outer-membrane protein fulfilling the criteria proposed for a receptor of mitochondrial precursor proteins. MOM19 seems to function as a `master receptor' for most--but not all--precursors.

"The interaction of precursor proteins with MOM19 is the first step of the complex pathway of protein import into mitochondria. The identification of MOM19 now provides the basis for determining the critical regions and structures of the receptor and the precursor proteins involved in high-affinity binding. In general, the identification of this receptor, and its biochemical and molecular characterization, should reveal insights into the essential and fascinating process of intracellular protein targeting."


R. Schule, K. Umesono, D.J. Mangelsdorf, J. Bolado, et al., "Jun-Fos and receptors for vitamins A and D recognize a common response element in the human osteocalcin gene," Cell, 61:497-504, 1990.

Roland Schule (Howard Hughes Medical Institute, The Salk Institute, La Jolla, Calif.): "Our paper integrates the action of steroid hormone receptors and protooncogenes. Steroids and related hormones, including those derived from vitamins A and D3, are often thought to induce cellular differentiation and are frequently associated with an inhibition of cell growth. In contrast, a number of protooncogenes encode nuclear proteins, such as c-Jun and c-Fos, that stimulate growth.

"Simplistically, cell growth and differentiation are thought of as opposing phenomena, and frequently, a terminally differentiated cell is also a post-mitotic cell. We present evidence that expression of the human osteocalcin gene is induced by both vitamins A and D3. Furthermore, overexpression of Jun/Fos suppresses both the basal level of the osteocalcin gene and the hormonal induction by vitamins A and D3. This unusual negative regulation, which probably occurs through a common response element, suggests a means by which growth factors can oppose the action of differentiation-inducing hormones. This provides a solution for the interplay of growth and differentiation factors."