| gene rearrangement, alpha-chain T-cell antigen receptor | Ordered rearrangement of T-cell variable gene regions coding for the alpha-chain of antigen receptors. (12 Dec 1998) |
|---|---|
| genes, T-cell receptor alpha | DNA sequences encoding the alpha chain of the T-cell receptor. The genomic organization of the tcr alpha genes is essentially the same in all species and is similar to the organization of ig genes. (12 Dec 1998) |
| receptors, adrenergic, alpha | One of the two major pharmacological subdivisions of adrenergic receptors. The alpha-beta distinction was originally based on cellular effects of receptor activation but now relies on the relative affinities for certain synthetic ligands. Alpha-adrenergic receptors are further subdivided into several subclasses based on studies of endogenous and cloned receptors. (12 Dec 1998) |
| receptors, adrenergic, alpha-1 | A subclass of alpha-adrenergic receptors (receptors, adrenergic, alpha). Alpha-1 adrenergic receptors can be pharmacologically discriminated, e.g., by their high affinity for the agonist phenylephrine and the antagonist prazosin. They are widespread, with clinically important concentrations in the liver, the heart, vascular, intestinal, and genitourinary smooth muscle, and the central and peripheral nervous systems. (12 Dec 1998) |
| receptors, adrenergic, alpha-2 | A subclass of alpha-adrenergic receptors (receptors, adrenergic, alpha). Alpha-2 adrenergic receptors can be pharmacologically discriminated, e.g., by their high affinity for the agonist clonidine and the antagonist yohimbine. They are found on pancreatic beta cells, platelets, and vascular smooth muscle, as well as both pre- and postsynaptically in the central and peripheral nervous systems. (12 Dec 1998) |
| receptors, antigen, T-cell, alpha-beta | T-cell receptors composed of CD3-associated alpha and beta polypeptide chains and expressed primarily in CD4+ or CD8+ T-cells. Unlike immunoglobulins, the alpha-beta T-cell receptors recognise antigens only when presented in association with major histocompatibility (MHC) molecules. (12 Dec 1998) |
| maternal serum alpha-fetoprotein | A plasma protein, alpha-fetoprotein (afp) is normally produced by the foetus. The level of afp in the blood serum of pregnant women provides a screening test for open neural tube defects (anencephaly and spina bifida) and for down syndrome (and other chromosome abnormalities). The maternal serum afp (msafp) tends to be unusally high with open neural tube defects and unsually low with down syndrome. (12 Dec 1998) |
| glucan 1,4-alpha-glucosidase | <enzyme> An enzyme that catalyses the hydrolysis of terminal 1,4-linked alpha-d-glucose residues successively from non-reducing ends of polysaccharide chains with the release of beta-glucose. It is also able to hydrolyze 1,6-alpha-glucosidic bonds when the next bond in sequence is 1,4. Chemical name: 1,4-alpha-D-Glucan glucohydrolase Registry number: EC 3.2.1.3 (12 Dec 1998) |
| glucan 1,4-alpha-maltohexaosidase | <enzyme> From klebsiella pneumoniae; hydrolyzes 1,4-alpha-d-glucosidic linkages in amylaceous polysaccharides so as to remove successive maltohexaose residues from the non-reducing ends Registry number: EC 3.2.1.98 Synonym: exo-maltohexao-hydrolase, extracellular maltohexaose-forming amylase, bacillus maltohexaose-forming amylase, g6-amylase (26 Jun 1999) |
| glucan 1,6-alpha-isomaltosidase | <enzyme> Hydrolyzes 1,6-alpha-d-glucosidic linkages in polysaccharides so as to remove successive isomaltose units from the non-reducing ends of the chains; from arthrobacter globiformis; mw 66 kD; genbank d30761 Registry number: EC 3.2.1.94 Synonym: isomalto-dextranase, 1,6-alpha-d-glucan isomaltohydrolase, imd gene product, exo-isomaltohydrolase (26 Jun 1999) |
| cephalosporin 7-alpha-hydroxylase | <enzyme> A dioxygenase from streptomyces clavuligerus; requires 2-oxoglutarate, fe2+ and a reducing agent such as ascorbic acid Registry number: EC 1.14.11.- (26 Jun 1999) |
| glycopeptide alpha-N-acetylgalactosaminidase | <enzyme> Hydrolyzes terminal d-galactosyl-n-acetyl-alpha-d-galactosaminide residues from glycopeptides and glycoproteins linked by serine or threonine residues Registry number: EC 3.2.1.97 Synonym: o-glycanase (26 Jun 1999) |
| glycoprotein endo-alpha-1,3-mannosidase | <enzyme> An endomannosidase; cleaves glucosyl alpha1-3-mannose from monoglucosylated oligosaccharide (glcman(7-9)glcnac) of the glycoprotein produced in the golgi membrane Registry number: EC 3.2.1.130 Synonym: glucosyl mannosidase (26 Jun 1999) |
| glycoprotein hormones, alpha subunit | A non-covalently bound subunit of the glycoprotein hormones tsh, fsh, lh, and hcg which originates in the anterior pituitary gland and placenta. This subunit is virtually identical in structure and indistinguishable by radioimmunoassay in all of the above glycoproteins. It is present in both men and women, but is elevated in postmenopausal women and in patients with hypothyroidism, uraemia and malignant tumours. The alpha subunit may be involved directly in recognition of certain receptors. (12 Dec 1998) |
| glycosylated alpha-amylase | <enzyme> Contains a single biantennary n-linked oligosaccharide that terminates with the structure fucalpha1,3(galbeta1,4)glcnac Registry number: EC 3.2.1.- Synonym: human glycosylated alpha-amylase (26 Jun 1999) |