Membrane contact sites are areas within a
cellThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
where the membranes of two
organelleIn cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid membrane....
s are arranged in close proximity. These sites are thought to be important in the transport of small molecules such as
lipidLipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others...
s between organelles, and offer an alternative to the classical mechanism of lipid transport through
vesiclesA vesicle is a bubble of liquid within a cell. More technically, a vesicle is a small, intracellular, membrane-enclosed sac that stores or transports substances within a cell. Vesicles form naturally because of the properties of lipid membranes ...
. Membrane contact sites may be particularly important in the function of the
endoplasmic reticulumThe endoplasmic reticulum is an eukaryotic organelle that forms an interconnected network of tubules, vesicles, and cisternae within cells. The lacey membranes of the endoplasmic reticulum were first seen by Keith R. Porter, Albert Claude, and Ernest F...
, since this is the major site of lipid synthesis within cells.
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Membrane contact sites are areas within a
cellThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
where the membranes of two
organelleIn cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid membrane....
s are arranged in close proximity. These sites are thought to be important in the transport of small molecules such as
lipidLipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, phospholipids, and others...
s between organelles, and offer an alternative to the classical mechanism of lipid transport through
vesiclesA vesicle is a bubble of liquid within a cell. More technically, a vesicle is a small, intracellular, membrane-enclosed sac that stores or transports substances within a cell. Vesicles form naturally because of the properties of lipid membranes ...
. Membrane contact sites may be particularly important in the function of the
endoplasmic reticulumThe endoplasmic reticulum is an eukaryotic organelle that forms an interconnected network of tubules, vesicles, and cisternae within cells. The lacey membranes of the endoplasmic reticulum were first seen by Keith R. Porter, Albert Claude, and Ernest F...
, since this is the major site of lipid synthesis within cells. These structures can form between the ER and many organelles, including mitochondria, peroxisomes, Golgi, peroxisomes, lysosomes and the plasma membrane. They can also form between other organelles, such as between the
cell nucleusIn cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as...
and the
vacuolethumb|400px|Plant cell structurethumb|400px|Animal cell structureA vacuole is a membrane organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells...
in yeast.