| CCAAT box | <molecular biology> Consensus sequence for RNA polymerase, found at about 80 bases relative to the transcription start site. Less well conserved than the TATA box. (18 Nov 1997) |
|---|---|
| Pribnow box | <molecular biology> A region of DNA to which RNA polymerase binds before initiating the transcription of DNA into RNA. The nucleotide at which transcription starts is designated +1 and nucleotides are numbered from this with negative numbers indicating upstream nucleotides and positive downstream nucleotides. most bacterial promoters contain two consensus sequences that seem to be essential for the binding of the polymerase. The first, the Pribnow box, is at about 10 and has the consensus sequence 5' TATAAT 3'. The second, the 35 sequence, is centred about 35 and has the consensus sequence 5' TTGACA 3'. most factors that regulate gene transcription do so by binding at or near the promoter and affecting the initiation of transcription. Much less is known about eukaryote promoters, each of the three RNA polymerases has a different promoter. RNA polymerase I recognises a single promoter for the precursor of rRNA. RNA polymerase II, that transcribes all genes coding for polypeptides, recognises many thousands of promoters. most have the Goldberg Hogness or TATA box that is centred around position 25 and has the consensus sequence 5' TATAAAA 3'. Several promoters have a CAAT box around 90 with the consensus sequence 5' GGCCAATCT 3'. There is increasing evidence that all promoters for housekeeping genes contain multiple copies of a GC rich element that includes the sequence 5' GGGCGG 3'. Transcription by polymerase II is also affected by more distant elements known as enhancers. RNA polymerase III synthesises 5s ribosomal RNA, all tRNAs and a number of small RNAs. The promoter for RNA polymerase III is located within the gene either as a single sequence, as in the 5s RNA gene or as two blocks, as in all tRNA genes. (13 Nov 1997) |
| Hogness box | <molecular biology> A consensus sequence found in the promoter region of most genes transcribed by eukaryotic RNA polymerase II. Found about 25 nucleotides before the site of initiation of transcription and has the consensus sequence: 5' TATAAAA 3'. This sequence seems to be important in determining accurately the position at which transcription is initiated. (18 Nov 1997) |
| Pu box | <molecular biology> Purine rich sequence recognised by the product of the Sp 1 oncogene. (18 Nov 1997) |
| snuff-box | See: anatomical snuffbox. (05 Mar 2000) |
| DEAD box helicase | <enzyme> Family of ATP dependent DNA or RNA helicases with a 4 amino acid consensus, D E A D, that resembles an ATP binding site. Examples, p68, a human nuclear protein involved in cell growth, vasa, a Drosophila protein required for specification of posterior embryonic structures. (18 Nov 1997) |
| androgen binding protein | A protein secreted by testicular Sertoli cells along with inhibin and mullerian inhibiting substance. Androgen binding protein probably maintains a high concentration of androgen in the seminiferous tubules. (05 Mar 2000) |
| antigen-binding site | <immunology> In immune network theory, an idiotope, an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the site on a ligand molecule to which a cell surface receptor binds. (18 Nov 1997) |
| binding | <biochemistry, chemistry, molecular biology> The adherence of molecules to one another, for example, enzymes to substrates, antibodies to antigens, DNA strands to their complementary strands. Binding occurs because the shape and chemical natures of parts of the molecules surfaces are complementary. A common metaphor is the "lock-and-key," used to describe how enzymes fit around their substrate. (14 Nov 1997) |
| binding constant | <chemistry> Reciprocal of dissociation constant. A measure of the extent of a reversible association between two molecular species at equilibrium. (18 Nov 1997) |
| binding energy | <chemistry, radiobiology> The binding energy of a nucleus is the minimum energy required to dissociate it into its component neutrons and protons. Neutron or proton binding energies are those required to remove a neutron or proton, respectively, from a nucleus. Electron binding energy is that required to remove an electron from an atom or a molecule. (16 Dec 1997) |
| binding sites | The reactive parts of a macromolecule that directly participate in its specific combination with another molecule. (12 Dec 1998) |
| binding sites, antibody | Local surface sites on antibodies which react with antigen determinant sites on antigens. They are formed from parts of the variable regions of the fab fragment of the immunoglobulin. (12 Dec 1998) |
| calcium-binding protein | <biochemistry> There are two main groups of calcium binding proteins, those that are similar to calmodulin and are called EF hand proteins and those that bind calcium and phospholipid (e.g. Lipocortin) and that have been grouped under the generic name of annexins. Many other proteins will bind calcium, although the binding site usually has considerable homology with the calcium-binding domains of calmodulin. They can act as transport proteins, regulator proteins or activator proteins. There is also a vitamin D-dependent variant which is a protein that plays a fundamental role in the vitamin d mediated transport of calcium in reptiles, amphibians, birds and mammals. It is found in the intestine, kidneys, egg shell gland, brain, and possibly other organs. Its molecular weight is species dependent. (12 May 2002) |
| cap binding protein | <molecular biology, protein> Protein (24 kD) with affinity for cap structure at 5' end of mRNA that probably assists, together with other initiation factors, in binding the mRNA to the 40S ribosomal subunit. Translation of mRNA in vitro is faster if it has a cap binding protein. (18 Nov 1997) |