| s | <radiobiology> Variable generally used for either entropy or the Poynting flux of electromagnetic wave energy (context makes clear which is meant). (09 Oct 1997) |
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| s & gs | See Standards and guidelines. (05 Dec 1998) |
| S antigen | Viral antigen that remains in solution after the particles of virus have been removed by means of centrifugation; in the case of the influenza viruses, it is the internal helical structure, free of the external envelope. Synonym: S antigen. (05 Mar 2000) |
| S factor | The individual variables, or empirically most minute subclusters of intercorrelations or common variance, found in different intelligence tests (specific). (05 Mar 2000) |
| S gene complex | <molecular biology> Genes coding for molecular components of the pollen stigma recognition system in the cabbage genus Brassica). The gene products govern the self incompatibility response and include a glycoprotein found on the stigma surface and a lectin on the pollen grain surface that binds to the stigma glycoprotein. (18 Nov 1997) |
| S layer | <biology> A continuous layer of glycoprotein or protein repeating units forming usually the outermost layer of several species of archae and eu bacteria. About 10 nm thick. (18 Nov 1997) |
| S phase | <cell biology> The phase of the cell cycle during which DNA replication takes place. (18 Nov 1997) |
| S potential | Prolonged, slow, depolarising or hyperpolarising responses to illumination; initiated between the photoreceptor and ganglion cell layers of the retina. (05 Mar 2000) |
| S protein | The major fragment produced from pancreatic ribonuclease by the limited action of subtilisin, which cleaves the ribonuclease between residues 20 and 21; the smaller fragment (residues 1-20) is S peptide. (05 Mar 2000) |
| S region | <molecular biology> The nonMHC gene in the midst of the H 2 major histocompatability complex of the mouse genome that codes for complement component C4. Sometimes confusingly known as the gene for the type III MHC product in mice. (12 Jan 1998) |
| S ring | <molecular biology> The static part of the bacterial motor: a ring of 15 or 17 sub units (one or less more than the M ring), anchored to the inner surface of the cell wall. (10 Mar 1998) |
| S romanum | Archaic term for sigmoid colon. (05 Mar 2000) |
| S sign of Golden | In pulmonary radiology, the combination of an atelectatic lobe and a central obstructing mass produces a concavity and a convexity, like the letter "S." (05 Mar 2000) |
| S type lectin | <protein> One of two classes of lectin produced by animal cells. The classification of animal lectins into two classes, the other being the C type, was originally proposed by K.Drickamer. The carbohydrate binding activity of the S type lectins requires their cysteines to have free thiols and does not need divalent cations (c.f. C type lectins). They mostly have molecular masses in the range 14-16 kD and often form dimers and higher oligomers. The carbohydrate recognition domain contains a number of critically conserved amino acids and largely binds to _ galactosides. S type lectins certainly occur as cytoplasmic proteins but the existence of extracellular S type lectins is still a matter of debate. (18 Nov 1997) |
| S value | Svedberg Unit. See: sedimentation coefficient. (18 Nov 1997) |