| trans-activation (genetics) | Increased rate of gene expression directed by either viral or cellular proteins. These regulatory factors (diffusible gene products) act in trans -- that is, act on homologous or heterologous molecules of DNA. (cis-acting factors act only on homologous molecules.) (12 Dec 1998) |
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| trans-activators | Diffusible gene products that act on homologous or heterologous molecules of viral or cellular DNA to regulate the expression of proteins. (12 Dec 1998) |
| trans-bronchial biopsy | <chest medicine, procedure> A biopsy that is performed through the wall of the bronchus (using the bronchoscope). This involves obtaining a small piece of lung tissue for microscopic analysis. This is a useful alternative to an open surgical biopsy, where an incision must be made. (17 Mar 1998) |
| trans configuration | 1. <chemistry> The configuration of an organic molecule containing a double bond between two carbon atoms, where the largest, most complex R groups attached to each carbon are on opposite sides. Alternatively: The configuration of an organic molecule containing a ring, where the largest, most complex R groups attached to each carbon are on opposite sides. These configurations are the opposite of cis configuration. 2. <genetics> A genetics term meaning that the changes in gene expression are due to something acting on the gene from a distance, or from an unrelated location, rather than on the same strand of DNA. Two mutations in different genes coding for the same phenotype which are on opposite homologous chromosomes (as opposed to the cis configuration where both of the mutations are on the same homologue). (17 Mar 1998) |
| trans Golgi network | <cell biology> A complex of membranous tubules and vesicles, near the trans face of the Golgi, which is thought to be a major intersection for intracellular traffic of vesicles. (18 Nov 1997) |
| trans-Golgi reticulum | That part of the Golgi apparatus that takes newly processed proteins and delivers them to secretory vesicles that will fuse with other biomembranes (e.g., the plasma membrane). (05 Mar 2000) |
| trans-octaprenyltranstransferase | <enzyme> Level of isopentenyl diphosphate-magnesium(ipp-mg) is decisive in affecting the chain length of the products of prenyltransferase reaction Registry number: EC 2.5.1.11 Synonym: solanesyl diphosphate synthase, solanesyl pyrophosphate synthetase (26 Jun 1999) |
| trans-pentaprenyltranstransferase | <enzyme> From micrococcus luteus b-p26; composed of 2 components; requires all-trans farnesyl or all-trans-geranylgeranyl pyrophosphate Registry number: EC 2.5.1.33 Synonym: all-trans-hexaprenylpyrophosphate synthase, hexaprenyldiphosphate synthetase, trans-pentaprenyltransferase, hexaprenylpyrophosphate synthetase (26 Jun 1999) |
| trans-retinal | The orange retinaldehyde resulting from the action of light on the rhodopsin of the retina, which converts the 11-cis-retinal component of the rhodopsin to all-trans-retinal plus opsin. Synonym: trans-retinal, visual yellow. (05 Mar 2000) |
| trans splicing | <molecular biology> Relating to RNA splicing of two different pre mRNA molecules together. Seems to rely on intron like sequences. Contrasts with the normal cis splicing of conventional RNA molecules. (19 Jan 1998) |
| trans-splicing | Formation of spliced products containing portions of two different transcripts. (05 Mar 2000) |