A receptor for protein import into potato mitochondria

• Published in: The Plant journal : for cell and molecular biology Vol. 9; no. 6; pp. 829 - 839
• Main Authors: Heins, Lisa, Schmitz, Udo Klaus
• Format: Journal Article
• Language: English
• Published: Osney Mead, Oxford OX2 0EL, UK Blackwell Science Ltd 01.06.1996; Blackwell Science
• Subjects: Amino Acid Sequence; Antibodies, Monoclonal; Base Sequence; Biological and medical sciences; Cell physiology; Cloning, Molecular; Fundamental and applied biological sciences. Psychology; Fungi - metabolism; Gene Library; Humans; Immunoglobulin G; Intracellular Membranes - metabolism; Mitochondria - metabolism; Molecular Sequence Data; Plant physiology and development; Plant Proteins - biosynthesis; Plant Proteins - chemistry; Plant Proteins - metabolism; Plasma membrane and permeation; Receptors, Cell Surface - biosynthesis; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - metabolism; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Homology, Amino Acid; Solanum tuberosum - metabolism; Trypsin; Membrane protein; Cell organelle; Nucleotide sequence; Antibody; Solanum tuberosum; Receiver; Characterization; Proteins; Mitochondria; Complementary DNA; Membrane transport; Dicotyledones; Angiospermae; Spermatophyta; Tuber plant; Solanaceae; Aminoacid sequence
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.1996.9060829.x

Summary Five potential surface receptors for protein import into plant mitochondria were identified by gentle trypsin treatment of intact mitochondria from potato tubers and subsequent preparation of outer mitochondrial membranes. One of them, a 23 kDa protein, was purified to homogeneity and analysed by direct protein sequencing. Copy DNA clones encoding the corresponding polypeptide were isolated with labelled oligonucleotides derived from the amino acid data. The 23 kDa protein shares significant sequence similarity with protein import receptors from fungal mitochondria and contains one of their typical tetratricopeptide motifs. Its integration into the outer membrane is independent of protease accessible surface receptors and not accompanied by proteolytic processing. Monospecific antibodies against the 23 kDa protein significantly reduce import capacity of isolated mitochondria indicating that this component is indeed involved in the recognition or import of precursor proteins. As in fungi, immunological inhibition of protein import with IgGs against a single receptor is incomplete suggesting the existence of other receptors in the outer mitochondrial membrane of plant mitochondria.