[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 04:00:00 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), Journal Name: American Journal of Human Genetics; (United States) Vol. 53:2; ISSN AJHGAG; ISSN 0002-9297
• Country of Publication: United States
• Language: English

Related Subjects

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