Biomaterial Database

The plant 73 kDa peroxisomal membrane protein (PMP73) is immunorelated to molecular chaperones. 1997

F J Corpas, and R N Trelease

Department of Botany, Arizona State University, Tempe 85287-1601, USA.

We previously showed via electron microscopic immunocytochemistry that a 73 kDa polypeptide was an authentic peroxisomal membrane protein (PMP73) integrated exclusively into the boundary membrane of glyoxysomes in cucumber seedlings. In this paper we test the hypothesis that this PMP73 is a member of the heat-shock 70 protein (Hsp70) family by comparing amino acid sequences of cyanogen bromide (CNBr)-cleaved polypeptide fragments, immunoreactivities on protein blots, and microscopic immunofluorescence within suspension-cultured BY-2 tobacco cells. A sequence of eight amino acids (DAVGPEIQ) in PMP73 showed a high degree of similarity (up to 88%) with sequences in the same carboxy-terminal region of four plant Hsp70 proteins. IgGs affinity purified to PMP73 recognized on blots a membrane-bound Hsp72 (in pea cotyledon microsomes) and a cucumber PMP61, the latter shown by CNBr cleavage to be a distinct, but immunorelated polypeptide to PMP73. Conversely, IgGs specific for tomato Hsc70 (C-terminal half) recognized cucumber PMP73, and IgGs specific for cucumber DnaJ homologue (entire protein) recognized cucumber PMP61. In BY-2 cells, cucumber PMP73-specific IgGs localized only to peroxisomes. Antibodies raised against portions of tomato Hsc70 also localized to the BY-2 peroxisomes (as well as to cytosolic proteins). Collectively, the data show that authentic cucumber PMPs73 and 61 are immunorelated to each another, and that both exhibit selective immunoreactivity to IgGs from two classes of molecular chaperones, namely Hsp70 proteins and plant DnaJ homologues. They appear to be unique membrane-bound chaperones that likely function as part of the peroxisomal protein translocation machinery.

UI	MeSH Term	Description	Entries
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D008856	Microscopy, Fluorescence	Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.	Fluorescence Microscopy,Immunofluorescence Microscopy,Microscopy, Immunofluorescence,Fluorescence Microscopies,Immunofluorescence Microscopies,Microscopies, Fluorescence,Microscopies, Immunofluorescence
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D010940	Plant Proteins	Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which PLANT PROTEINS, DIETARY is available.	Plant Protein,Protein, Plant,Proteins, Plant
D017386	Sequence Homology, Amino Acid	The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.	Homologous Sequences, Amino Acid,Amino Acid Sequence Homology,Homologs, Amino Acid Sequence,Homologs, Protein Sequence,Homology, Protein Sequence,Protein Sequence Homologs,Protein Sequence Homology,Sequence Homology, Protein,Homolog, Protein Sequence,Homologies, Protein Sequence,Protein Sequence Homolog,Protein Sequence Homologies,Sequence Homolog, Protein,Sequence Homologies, Protein,Sequence Homologs, Protein
D018532	Pisum sativum	A variable annual leguminous vine that is cultivated for its rounded smooth or wrinkled edible protein-rich seeds, the seed of the pea, and the immature pods with their included seeds. (From Webster's New Collegiate Dictionary, 1973)	Peas,Pisum,Pea
D018553	Cucumis sativus	A creeping annual plant species of the CUCURBITACEAE family. It has a rough succulent, trailing stem and hairy leaves with three to five pointed lobes.	Cucumber,Cucumbers
D018832	Molecular Chaperones	A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures.	Chaperones, Molecular,Chaperone, Molecular,Molecular Chaperone
D018840	HSP70 Heat-Shock Proteins	A class of MOLECULAR CHAPERONES found in both prokaryotes and in several compartments of eukaryotic cells. These proteins can interact with polypeptides during a variety of assembly processes in such a way as to prevent the formation of nonfunctional structures.	Heat-Shock Proteins 70,Heat Shock 70 kDa Protein,Heat-Shock Protein 70,HSP70 Heat Shock Proteins,Heat Shock Protein 70,Heat Shock Proteins 70,Heat-Shock Proteins, HSP70