[beta]-hexosaminidase isozymes from cells cotransfected with [alpha] and [beta] cDNA constructs: Analysis of the [alpha]-subunit missense mutation associated with the adult form of Tay-Sachs disease

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · American Journal of Human Genetics; (United States)

OSTI ID:5852487

Brown, C A; Mahuran, D J ^[1]

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1. Univ. of Toronto (Canada)

In vitro mutagenesis and transient expression in COS cells has been used to associate a missense mutation with a clinical or biochemical phenotype. Mutations affecting the [alpha]-subunit of [beta]-hexosaminidase A ([alpha][beta]) (E.C.3.2.1.52) result in Tay-Sachs disease. Because hexosaminidase A is heterodimeric, analysis of [alpha]-chain mutations is not straightforward. The authors examine three approaches utilizing previously identified mutations affecting [alpha]-chain folding. These involve transfection of (1) the [alpha] cDNA alone; (2) a [beta] cDNA construct encoding a [beta]-subunit substituted at a position homologous to that of the [alpha]-subunit, and (3) both [alpha] and [beta] cDNAs. The latter two procedures amplified residual activity levels over that of patient samples, an effect not previously found with mutations affecting an [open quotes]active[close quotes] [alpha]Arg residue. This effect may help to discriminate between protein-folding and active-site mutations. The authors conclude that, with proper controls, the latter method of cotransfection can be used to evaluate the effects and perhaps to predict the clinical course of some [alpha]-chain mutations. Using this technique, they demonstrate that the adult-onset Tay-Sachs mutation, [alpha]Gly[yields]Ser[sup 269], does not directly affect [alpha][beta] dimerization but exerts an indirect effect on the dimer through destabilizing the folded [alpha]-subunit at physiological temperatures. Two other [alpha] mutations linked to more severe phenotypes appear to inhibit the initial folding of the subunit. 36 refs., 2 figs., 5 tabs.

• OSTI ID: 5852487
• Journal Information: American Journal of Human Genetics; (United States), Vol. 53:2; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CEREBROSIDES
METABOLIC DISEASES
ENZYMES
DIMERIZATION
GENE MUTATIONS
GANGLIOSIDES
HEXOSAMINES
ENZYMATIC HYDROLYSIS
SPHINGOMYELINS
HEREDITARY DISEASES
PROTEIN STRUCTURE
AMINES
CARBOHYDRATES
CHEMICAL REACTIONS
DECOMPOSITION
DISEASES
ESTERS
GLYCOLIPIDS
HEXOSES
HYDROLYSIS
LIPIDS
LYSIS
MONOSACCHARIDES
MUTATIONS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
POLYMERIZATION
PROTEINS
SACCHARIDES
SOLVOLYSIS
550400* - Genetics
550900 - Pathology