Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms involved in the targeting of proteins to different cytosolic compartments are still largely unknown. In this study we have investigated the targeting signal of the 65-kD isoform of glutamic acid decarboxylase (GAD65), a major autoantigen in two autoimmune diseases: Stiff-Man syndrome and insulin-dependent diabetes mellitus. GAD65 is expressed in neurons and in pancreatic beta-cells, where it is concentrated in the Golgi complex region and in proximity to GABA-containing vesicles. GAD65, but not the similar isoform GAD67 which has a more diffuse cytosolic distribution, is palmitoylated within its first 100 amino acids (a.a.). We have previously demonstrated that the domain corresponding to a.a. 1-83 of GAD65 is required for the targeting of GAD65 to the Golgi complex region. Here we show that this domain is sufficient to target an unrelated protein, beta-galactosidase, to the same region. Site-directed mutagenesis of all the putative acceptor sites for thiopalmitoylation within this domain did not abolish targeting of GAD65 to the Golgi complex region. The replacement of a.a. 1-29 of GAD67 with the corresponding a.a. 1-27 of GAD65 was sufficient to target the otherwise soluble GAD67 to the Golgi complex region. Conversely, the replacement of a.a. 1-27 of GAD65 with a.a. 1-29 of GAD67 resulted in a GAD65 protein that had a diffuse cytosolic distribution and was primarily hydrophilic, suggesting that targeting to the Golgi complex region is required for palmitoylation of GAD65. We propose that the domain corresponding to a.a. 1-27 of GAD65, contains a signal required for the targeting of GAD65 to the Golgi complex region.
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PMID:A signal located within amino acids 1-27 of GAD65 is required for its targeting to the Golgi complex region. 803 38

An 18-month-old girl was diagnosed as having GM1 gangliosidosis, on the basis of the clinical symptoms of muscle stiffness, developmental retardation, hepatosplenomegaly, and kyphoscoliosis and a laboratory study that revealed a deficiency in the lysosomal degradative enzyme beta-galactosidase. Magnetic resonance T1-weighted images showed persistent hyperintensity in the bilateral thalami, brainstem, and deep cerebellum at 14 and 18 months of age, indicating arrest of the myelination process in these areas, and that the arrest had occurred at the newborn stage. There was no myelination in the basal ganglia and diffuse leukomalacia developed in the cerebral hemispheres. Only supportive treatment was given; the patient died at 2 years of age. Myelination arrest at the newborn stage associated with progressive leukomalacia is a possible characteristic of GM1 gangliosidosis.
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PMID:Myelination arrest demonstrated using magnetic resonance imaging in a child with type I GM1 gangliosidosis. 958 85