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Porosomes
440px 280px Porosomes are cup-shaped supramolecular structures in the cell membranes of eukaryotic cells where secretory vesicles transiently dock in the process of vesicle fusion and secretion. The transient fusion of secretory vesicle membrane at a porosome, base via SNARE proteins, results in the formation of a fusion pore or continuity for the release of intravesicular contents from the cell. After secretion is complete, the fusion pore temporarily formed at the base of the porosome is sealed. Porosomes are few nanometers in size and contain many different types of protein, especially chloride and calcium channels, actin, and SNARE proteins that mediate the docking and fusion of the vesicles with the cell membrane. Once the vesicles have docked with the SNARE proteins, they swell, which increases their internal pressure. They then transiently fuse at the base of the porosome, and these pressurized contents are ejected from the cell. Examination of cells following secretio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secretory Mechanism
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell (biology), cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the Cell membrane, plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures embedded in the cell membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell. Bacterial secretion system, Secretion in bacterial species means the transport or translocation of effector molecules. For example: proteins, enzymes or toxins (such as cholera toxin in pathogenic bacteria e.g. ''Vibrio cholerae'') from across the interior (cytoplasm or cytosol) of a bacterial cell to its exterior. Secretion is a very important mechanism in bacterial functioning and operation in their natural surrounding environment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secretory Vesicle
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures embedded in the cell membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell. Secretion in bacterial species means the transport or translocation of effector molecules. For example: proteins, enzymes or toxins (such as cholera toxin in pathogenic bacteria e.g. ''Vibrio cholerae'') from across the interior (cytoplasm or cytosol) of a bacterial cell to its exterior. Secretion is a very important mechanism in bacterial functioning and operation in their natural surrounding environment for adaptation and survival. In eukaryotic cells Mechan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secretion
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures embedded in the cell membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell. Secretion in bacterial species means the transport or translocation of effector molecules. For example: proteins, enzymes or toxins (such as cholera toxin in pathogenic bacteria e.g. '' Vibrio cholerae'') from across the interior (cytoplasm or cytosol) of a bacterial cell to its exterior. Secretion is a very important mechanism in bacterial functioning and operation in their natural surrounding environment for adaptation and survival. In eukaryotic cells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membranes
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic molecule ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of Outline of life forms, life forms alongside the two groups of prokaryotes: the Bacteria and the Archaea. Eukaryotes represent a small minority of the number of organisms, but given their generally much larger size, their collective global biomass is much larger than that of prokaryotes. The eukaryotes emerged within the archaeal Kingdom (biology), kingdom Asgard (Archaea), Promethearchaeati and its sole phylum Promethearchaeota. This implies that there are only Two-domain system, two domains of life, Bacteria and Archaea, with eukaryotes incorporated among the Archaea. Eukaryotes first emerged during the Paleoproterozoic, likely as Flagellated cell, flagellated cells. The leading evolutiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesicle Fusion
Vesicle fusion is the merging of a vesicle with other vesicles or a part of a cell membrane. In the latter case, it is the end stage of secretion from secretory vesicles, where their contents are expelled from the cell through exocytosis. Vesicles can also fuse with other target cell compartments, such as a lysosome. Exocytosis occurs when secretory vesicles transiently dock and fuse at the base of cup-shaped structures at the cell plasma membrane called porosomes, the universal secretory machinery in cells. Vesicle fusion may depend on SNARE proteins in the presence of increased intracellular calcium (Ca2+) concentration. Triggers Stimuli that trigger vesicle fusion act by increasing intracellular Ca2+. * Synaptic vesicles commit vesicle fusion by a nerve impulse reaching the synapse, activating voltage-dependent calcium channels that cause influx of Ca2+ into the cell. * In the endocrine system, many hormones are released by their releasing hormones binding to G protein cou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SNARE (protein)
SNARE proteins – " SNAP REceptors" – are a large protein family consisting of at least 24 members in yeasts and more than 60 members in mammalian and plant cells. The primary role of SNARE proteins is to mediate the fusion of vesicles with the target membrane; this notably mediates exocytosis, but can also mediate the fusion of vesicles with membrane-bound compartments (such as a lysosome). The best studied SNAREs are those that mediate the release of synaptic vesicles containing neurotransmitters in neurons. These neuronal SNAREs are the targets of the neurotoxins responsible for botulism and tetanus produced by certain bacteria. Types SNAREs can be divided into two categories: ''vesicle'' or ''v-SNAREs'', which are incorporated into the membranes of transport vesicles during budding, and ''target'' or ''t-SNAREs'', which are associated with nerve terminal membranes. Evidence suggests that t-SNAREs form stable subcomplexes which serve as guides for v-SNARE, incorpo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesicle (biology And Chemistry)
In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion ( exocytosis), uptake (endocytosis), and the transport of materials within the plasma membrane. Alternatively, they may be prepared artificially, in which case they are called liposomes (not to be confused with lysosomes). If there is only one phospholipid bilayer, the vesicles are called ''unilamellar liposomes''; otherwise they are called ''multilamellar liposomes''. The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle. Vesicles perform a variety of functions. Because it is separated from the cytosol, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bhanu Pratap Jena
Bhanu Pratap Jena (born November 1, 1955) is an American cell biologist and the George E. Palade University Professor and Distinguished Professor of Physiology at the Wayne State University School of Medicine, who discovered porosome in the mid-1990s and demonstrated it to be the universal secretory machinery in plasma membrane. Biography Jena was born in Jajpur, Odisha, India on November 1, 1955, to Manju and Prafulla Jena. He majored in Chemistry, Zoology and Botany at BJB College (B.Sc.,1975) and studied Zoology (Endocrinology) at Utkal University (M.Sc.,1978). Following four years of lectureship at various colleges in Utkal University (1978–82), he received a teaching and research fellowship from Iowa State University in 1982 to pursue studies leading to a doctorate degree. In December 1988, he received his PhD in Zoology (Molecular Endocrinology) from Iowa State. Following postdoctoral studies at Iowa State and Yale (1988–1994), he joined Yale University as an assistan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yale University
Yale University is a Private university, private Ivy League research university in New Haven, Connecticut, United States. Founded in 1701, Yale is the List of Colonial Colleges, third-oldest institution of higher education in the United States, and one of the nine colonial colleges chartered before the American Revolution. Yale was established as the Collegiate School in 1701 by Congregationalism in the United States, Congregationalist clergy of the Connecticut Colony. Originally restricted to instructing ministers in theology and sacred languages, the school's curriculum expanded, incorporating humanities and sciences by the time of the American Revolution. In the 19th century, the college expanded into graduate and professional instruction, awarding the first Doctor of Philosophy, PhD in the United States in 1861 and organizing as a university in 1887. Yale's faculty and student populations grew rapidly after 1890 due to the expansion of the physical campus and its scientif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Force Microscopy
Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. Overview Atomic force microscopy (AFM) gathers information by "feeling" or "touching" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable precise scanning. Despite the name, the Atomic Force Microscope does not use the nuclear force. Abilities and spatial resolution The AFM has three major abilities: force measurement, topographic imaging, and manipulation. In force measurement, AFMs can be used to measure the forces between the probe and the sample as a function of their mutual separation. This can be applied to perform force spectroscopy, to measure the mechanical properties of the sample, such as the sample's Youn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
