Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.6.1 (sulfatase)
 3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have tried to characterize the intracellular compartments involved in the traffic of the thyroid prohormone thyroglobulin (Tg) from the site of storage, the follicular lumen, to the expected site(s) of proteolytic degradation, lysosomes. Electron microscope immunogold labeling with antibodies against Tg, cation-independent mannose-6-phosphate receptor (MPR), or arylsulfatase-A (ArS-A) was used to identify endocytic structures. The implication of these structures in the transport of Tg was analyzed by following the internalization and intracellular fate of Tg-colloidal gold complexes microinjected into the thyroid follicular lumen. Immunogold labeling was performed on ultrathin cryosections of intact pig tissue, in vitro reconstituted thyroid follicles (RTF), and isolated vesicles prepared by differential and isopycnic centrifugation. Microinjection experiments were carried out on RTF. Using double labeling for MPR and ArS-A, we characterized three types of structures: those slightly positive for MPR and ArS-A, those strongly positive for both markers, and those only positive for ArS-A. These compartments exhibited the properties of early endosomes (EE), late endosomes (LE), and lysosomes (L), respectively. Tg immunoreactivity was high in EE, low in LE, and undetectable in L. Similar morphological and immunochemical characteristics of EE, LE, and L were found in intact tissue, RTF, and isolated vesicles. Tg-gold complexes microinjected into the lumen of RTF were efficiently internalized within 5 min into structures with the appearance of EE. Sixty minutes after the injection, Tg-gold complexes were detected into LE and L. We present here the first direct experimental evidence for an involvement of endosomal compartments in the Tg internalization/degradation pathway. The data indicate that internalized Tg molecules are transported to EE and then transferred from EE to LE.
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PMID:Thyroglobulin internalized by thyrocytes passes through early and late endosomes. 191 1

In addition to their general function in cellular homeostasis, thyroid lysosomes play an essential role in the biosynthesis of thyroid hormones by cleaving the macromolecular prohormone, thyroglobulin. In the present work, we have attempted to determine whether the enzyme composition of thyroid lysosomes differs from that of lysosomes from other tissues. Lysosomal enzymes, cathepsin D, beta-D-galactosidase, beta-D-glucosidase, alpha-D-mannosidase, alpha-L-fucosidase, hexosaminidase, and arylsulfatase A and B, were assayed in crude fractions from various pig tissues, heart, brain, liver, kidney, thyroid, adrenals, ovary, and spleen. It appeared that the specific activity of arylsulfatase A was at least 20 times higher in the thyroid than in most other tissues. Thyroid lysosomes purified by isopycnic centrifugation on Percoll gradients contained two major polypeptides with apparent molecular weights of 58,000 and 54,000 representing about 30% of the total protein. These polypeptides were glycosylated and were exclusively found in the intralysosomal soluble fraction obtained by osmotic pressure-dependent lysis. By fractionating intralysosomal soluble proteins by velocity sedimentation on sucrose gradients or gel permeation chromatography we identified a thyroid arylsulfatase A holoenzyme which corresponds to a 120,000 Mr species. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of the gradient or column fractions showed that the 120-kDa protein peak with arylsulfatase A activity essentially contained the 58- and 54-kDa polypeptides in equivalent amounts. In conclusion, arylsulfatase A, a heterodimer of 120 kDa composed of two nonidentical subunits, is the major protein component of thyroid lysosomes. The superabundance of this protein in purified thyroid lysosomes is related to the very high specific activity of the enzyme in the thyroid as compared to other tissues.
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PMID:Evidence for the presence of a very high concentration of arylsulfatase A in the pig thyroid: identification of arylsulfatase A subunits as the two major glycoproteins in purified thyroid lysosomes. 256 93

A benztropine RIA based on polyclonal antisera raised in New Zealand white rabbits has been developed. The drug-protein conjugates employed had a variety of moles of benztropine hemisuccinate coupled per mole of protein (bovine serum albumin or bovine thyroglobulin). Six antisera were developed and the one with the highest titer was further evaluated for its cross reactivity to N-desmethylbenztropine (4%) and the antipsychotic agents fluphenazine, flupenthixol, chlorpromazine, and haloperidol (all < 1%). The selected antiserum demonstrated sufficient sensitivity to measure benztropine from 0.156 to 100 ng/mL plasma in a 200-microL plasma sample, with a mean CV of < 6%. The RIA was applied to the analysis of steady-state plasma samples obtained from patients undergoing treatment with benztropine and plasma samples obtained from human volunteers and dogs orally dosed with the drug. Both the human and dog plasma samples, when analyzed after hydrolysis with beta-glucuronidase/sulfatase, demonstrated increments in benztropine concentrations, suggesting the drug may be undergoing biotransformation to phase II metabolite(s). In addition, when benztropine was selectively extracted from the unhydrolyzed plasma samples, there was a significant decrease in drug level, which further suggested that the antiserum cross reacted with phase II metabolite(s). The shape of the plasma concentration versus time profile obtained from the dog studies suggested that the drug might also undergo enterohepatic recycling.
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PMID:Development of a sensitive and specific radioimmunoassay for benztropine. 825 87