| membrane recycling | <cell biology> The process whereby membrane is internalised, fuses with an internal membranous compartment and is then re incorporated into the plasma membrane. In cells that are actively secreting by an exocrine method (in which secretory granules fuse with the plasma membrane), it is obviously essential to have some way of reducing the area of the plasma membrane. The membrane can then be used to form new secretory vesicles. The converse is true for phagocytic cells. (18 Nov 1997) |
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| membrane transport | <cell biology> The transfer of a substance from one side of a plasma membrane to the other, in a specific direction and at a rate faster than diffusion alone. See: active transport. (18 Nov 1997) |
| membrane-type 3 matrix metalloproteinase | <enzyme> Sm3 is a soluble form of mt3-mmp, probably an alternatively sliced variant. Registry number: EC 3.4.24.- Synonym: mt3-mmp, sm3-mmp (26 Jun 1999) |
| membrane-type 4 matrix metalloproteinase | <enzyme> Cloned from breast carcinoma. Registry number: EC 3.4.24.- Synonym: mt4-mmp, mmp-17 gene product, mmp-17 (26 Jun 1999) |
| membrane-type matrix metalloproteinase | <enzyme> Activates gelatinase a; isolated from a human placenta cdna gene library; contains a transmembrane domain; do not use for any other numbered matrix metalloproteinases; genbank d26512 Registry number: EC 3.4.24.- Synonym: mt-mmp, mmp-x1 protein, matrix metalloproteinase, membrane-type, mmp14 gene product, mmp-14 gene product, mt1-mmp, matrix metalloproteinase 14, mt2-mmp, mmp15 gene product, mmp16 gene product (26 Jun 1999) |
| membrane vesicle | <cell biology> Closed unilamellar shells formed from membranes either in physiological transport processes or else when membranes are mechanically disrupted. They form spontaneously when membrane is broken because the free ends of a lipid bilayer are highly unstable. (18 Nov 1997) |
| membrane zippering | <cell biology> Process suggested to occur in phagocytosis in which the membrane of the phagocyte covers the particle by a progressive adhesive interaction. The evidence for such a mechanism comes from experiments in which capped B-cells are only partially internalised, whereas those with a uniform opsonising coat of antiIgG are fully engulfed. (18 Nov 1997) |
| peribacteroid membrane | <plant biology> Membrane derived from the plasma membrane of a plant cell and that surrounds the nitrogen fixing bacteroids in legume root nodules. Has a high lipid content and may regulate the passage of material from the plant cell cytoplasm to the symbiotic bacterial cell. The idea that it restricts leghaemoglobin to the peribacteroid space seems untenable since leghaemoglobin is found in the cytoplasm of some cells. (18 Nov 1997) |
| pericardiopleural membrane | A tissue fold jutting into the right or left embryonic pericardioperitoneal canal; it separates the developing pericardium from the pleural cavity and is formed by the growth of the common cardinal veins to the midline of the body. Synonym: pericardiopleural membrane, pleuropericardial membrane. (05 Mar 2000) |
| pericolic membrane syndrome | <syndrome> A symptom complex simulating chronic appendicitis, caused by congenital constricting pericolic membranes. (05 Mar 2000) |
| peridental membrane | <anatomy> Fibrous connective tissue surrounding the root of a tooth that separates it from and attaches it to the alveolar bone. (12 Dec 1998) |
| perineal membrane | The layer of fascia extending between the ischiopubic rami inferior to the sphincter urethrae and the deep transverse perineal muscles. Synonym: membrana perinei, fascia diaphragmatis urogenitalis inferior, Camper's ligament, ligamentum triangulare, perineal membrane, triangular ligament. (05 Mar 2000) |
| periodontal membrane | <anatomy> Fibrous connective tissue surrounding the root of a tooth that separates it from and attaches it to the alveolar bone. (12 Dec 1998) |
| periorbital membrane | The periosteum of the orbit. Synonym: periorbit, periorbital membrane. Origin: peri-+ L. Orbita, orbit (05 Mar 2000) |
| peripheral membrane protein | <protein> Membrane proteins that are bound to the surface of the membrane and not integrated into the hydrophobic region. Usually soluble and were originally thought to bind to integral proteins by ionic and other weak forces (and could therefore be removed by high ionic strength, for example). However, it is now clear that some peripheral membrane proteins are covalently linked to molecules that are part of the membrane bilayer (see acylated proteins and glypiation) and that there are others that fit the original definition but are perhps more appropriately considered proteins of the cytoskeleton (e.g. Band 4.1 and spectrin) or extracellular matrix (e.g. Fibronectin). (18 Nov 1997) |