Interaction between constitutively expressed heat shock protein, Hsc 70, and cysteine string protein is important for cortical granule exocytosis in Xenopus oocytes. 2005

Geoffrey B Smith, and Joy A Umbach, and Arlene Hirano, and Cameron B Gundersen
Department of Molecular and Medical Pharmacology, David P. Geffen UCLA School of Medicine, Los Angeles, California 90095, USA.

In many species, binding of sperm to the egg initiates cortical granule exocytosis, an event that contributes to a sustained block of polyspermy. Interestingly, cortical granule exocytosis can be elicited in immature Xenopus oocytes by the protein kinase C activator, phorbol-12-myristate-13-acetate. In this study, we investigated the role of cysteine string protein (csp) in phorbol-12-myristate-13-acetate-evoked cortical granule exocytosis. Prior work indicated that csp is associated with cortical granules of Xenopus oocytes. In oocytes exhibiting >20-fold overexpression of full-length Xenopus csp, cortical granule exocytosis was reduced by approximately 80%. However, csp overexpression did not affect constitutive exocytosis. Subcellular fractionation and confocal fluorescence microscopy revealed that little or none of the overexpressed csp was associated with cortical granules. This accumulation of csp at sites other than cortical granules suggested that mislocalized csp might sequester a protein that is important for regulated exocytosis. Because the NH2-terminal region of csp includes a J-domain, which interacts with constitutively expressed 70-kDa heat shock proteins (Hsc 70), we evaluated the effect of overexpressing the J-domain of csp. Although the native J-domain of csp inhibited cortical granule exocytosis, point mutations that interfere with J-domain binding to Hsc 70 eliminated this inhibition. These data indicate that csp interaction with Hsc 70 molecular chaperones is vital for regulated secretion in Xenopus oocytes.

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
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D009865 Oocytes Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM). Ovocytes,Oocyte,Ovocyte
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D011500 Protein Synthesis Inhibitors Compounds which inhibit the synthesis of proteins. They are usually ANTI-BACTERIAL AGENTS or toxins. Mechanism of the action of inhibition includes the interruption of peptide-chain elongation, the blocking the A site of ribosomes, the misreading of the genetic code or the prevention of the attachment of oligosaccharide side chains to glycoproteins. Protein Synthesis Antagonist,Protein Synthesis Antagonists,Protein Synthesis Inhibitor,Antagonist, Protein Synthesis,Antagonists, Protein Synthesis,Inhibitor, Protein Synthesis,Inhibitors, Protein Synthesis,Synthesis Antagonist, Protein,Synthesis Inhibitor, Protein
D005089 Exocytosis Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012313 RNA A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated
D013347 Subcellular Fractions Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163) Fraction, Subcellular,Fractions, Subcellular,Subcellular Fraction
D013755 Tetradecanoylphorbol Acetate A phorbol ester found in CROTON OIL with very effective tumor promoting activity. It stimulates the synthesis of both DNA and RNA. Phorbol Myristate Acetate,12-Myristoyl-13-acetylphorbol,12-O-Tetradecanoyl Phorbol 13-Acetate,Tetradecanoylphorbol Acetate, 4a alpha-Isomer,12 Myristoyl 13 acetylphorbol,12 O Tetradecanoyl Phorbol 13 Acetate,13-Acetate, 12-O-Tetradecanoyl Phorbol,Acetate, Phorbol Myristate,Acetate, Tetradecanoylphorbol,Myristate Acetate, Phorbol,Phorbol 13-Acetate, 12-O-Tetradecanoyl,Tetradecanoylphorbol Acetate, 4a alpha Isomer

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