- Publikační typ
- abstrakt z konference MeSH
Transmembrane adaptor proteins are membrane-anchored proteins consisting of a short extracellular part, a transmembrane domain, and a cytoplasmic part with various protein-protein interaction motifs but lacking any enzymatic activity. They participate in the regulation of various signaling pathways by recruiting other proteins to the proximity of cellular membranes where the signaling is often initiated and propagated. In this work, we show that LST1/A, an incompletely characterized protein encoded by MHCIII locus, is a palmitoylated transmembrane adaptor protein. It is expressed specifically in leukocytes of the myeloid lineage, where it localizes to the tetraspanin-enriched microdomains. In addition, it binds SHP-1 and SHP-2 phosphatases in a phosphotyrosine-dependent manner, facilitating their recruitment to the plasma membrane. These data suggest a role for LST1/A in negative regulation of signal propagation.
- MeSH
- buněčná membrána metabolismus MeSH
- HEK293 buňky MeSH
- HeLa buňky MeSH
- hlavní histokompatibilní komplex fyziologie MeSH
- Jurkat buňky MeSH
- lidé MeSH
- membránové proteiny chemie genetika metabolismus MeSH
- molekulární sekvence - údaje MeSH
- myeloidní buňky cytologie metabolismus MeSH
- plakiny metabolismus MeSH
- primární buněčná kultura MeSH
- pseudopodia metabolismus MeSH
- sekvence aminokyselin MeSH
- signální transdukce fyziologie MeSH
- terciární struktura proteinů fyziologie MeSH
- transport proteinů fyziologie MeSH
- tyrosinfosfatasa nereceptorového typu 11 metabolismus MeSH
- tyrosinfosfatasa nereceptorového typu 6 metabolismus MeSH
- U937 buňky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Membrane rafts and signaling molecules associated with them are thought to play important roles in immunoreceptor signaling. Rafts differ in their lipid and protein compositions from the rest of the membrane and are relatively resistant to solubilization by Triton X-100 or similar detergents, producing buoyant, detergent-resistant membranes (DRMs) that can be isolated by density gradient ultracentrifugation. One of the key signaling molecules present in T cell DRMs is the transmembrane adaptor protein LAT (linker for activation of T cells). In contrast to previous results, a recent study demonstrated that a LAT construct not present in the buoyant DRMs is fully able to support TCR signaling and development of T cells in vivo. This finding caused doubts about the real physiological role of rafts in TCR signaling. In this study, we demonstrate that these results can be explained by the existence of a novel type of membrane raft-like microdomains, producing upon detergent solubilization "heavy DRMs" containing a number of membrane molecules. At a moderate level of expression, LAT supported TCR signaling more efficiently than constructs targeted to the microdomains producing heavy DRMs or to nonraft membrane. We suggest that different types of membrane microdomains provide environments regulating the functional efficiencies of signaling molecules present therein.
- MeSH
- adaptorové proteiny signální transdukční imunologie metabolismus MeSH
- aktivace lymfocytů imunologie MeSH
- Jurkat buňky MeSH
- lidé MeSH
- membránové mikrodomény chemie imunologie MeSH
- membránové proteiny chemie imunologie izolace a purifikace metabolismus MeSH
- receptory antigenů T-buněk imunologie metabolismus MeSH
- signální transdukce imunologie MeSH
- T-lymfocyty chemie imunologie metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Acute intermittent porphyria is an autosomal dominantly inherited disorder, classified as acute hepatic porphyria, caused by a deficiency of hydroxymethylbilane synthase (EC 2.5.1.61, EC 4.3.1.8, also known as porphobilinogen deaminase, uroporphyrinogen I synthase), the third enzyme in heme biosynthesis. Clinical features include autonomous, central, motor or sensory symptoms, but the most common clinical presentation is abdominal pain caused by neurovisceral crises. A diagnosis of acute intermittent porphyria is crucial to prevent life-threatening acute attacks. Detection of DNA variations by molecular techniques allows a diagnosis of acute intermittent porphyria in situations where the measurement of porphyrins and precursors in urine and faeces and erythrocyte hydroxymethylbilane synthase activity is inconclusive. In the present study, we identified gene defects in six Czech patients with acute intermittent porphyria, as diagnosed based on biochemical findings, and members of their families to confirm the diagnosis at the molecular level and/or to provide genetic counselling. Molecular analyses of the hydroxymethylbilane synthase gene revealed seven mutations. Four were previously reported: c.76C>T, c.77G>A, c.518G>A, c.771 + 1G>T (p.Arg26Cys, p.Arg26His, p.Arg173Gln). Three were novel mutations: c.610C>A, c.675delA, c.750A>T (p.Gln204Lys, p.Ala226ProfsX28, p.Glu250Asp). Of particular interest, one patient had two mutations (c.518G>A; c.610C>A), both located in exon 10 of the same allele. To establish the effects of the mutations on enzyme function, biochemical characterization of the expressed normal recombinant and mutated proteins was performed. Prokaryotic expression of the mutant alleles of the hydroxymethylbilane synthase gene revealed that, with the exception of the p.Gln204Lys mutation, all mutations resulted in little, if any, enzymatic activity. Moreover, the 3D structure of the Escherichia coli and human protein was used to interpret structure-function relationships for the mutations in the human isoform.
- MeSH
- akutní intermitentní porfyrie diagnóza enzymologie genetika MeSH
- Escherichia coli enzymologie genetika metabolismus MeSH
- financování organizované MeSH
- hydroxymethylbilansynthasa genetika metabolismus MeSH
- konformace proteinů MeSH
- lidé MeSH
- molekulární modely MeSH
- molekulární sekvence - údaje MeSH
- mutace MeSH
- mutační analýza DNA MeSH
- sekvence nukleotidů MeSH
- substituce aminokyselin MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
Acute intermittent porphyria (AIP) is an autosomal dominant disorder of heme biosynthesis caused by molecular defects in the porphobilinogen deaminase (PBGD) gene. This paper reviews published mutations, their types, and polymorphisms within the PBGD gene. To date, 301 different mutations and 21 polymorphisms have been identified in the PBGD gene in AIP patients and individuals from various countries and ethnic groups. During the search for mutations identified among Slavic AIP patients we found 65 such mutations and concluded that there is not a distinct predominance of certain mutations in Slavs.
- MeSH
- akutní intermitentní porfyrie epidemiologie genetika MeSH
- běloši genetika MeSH
- hydroxymethylbilansynthasa genetika MeSH
- lidé MeSH
- mutace * MeSH
- polymorfismus genetický * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- srovnávací studie MeSH
The porphyrias are group of mostly inherited disorders in which a specific spectrum of accumulated and excreted porphyrins and heme precursors are associated with characteristic clinical features. There are eight enzymes involved in the heme synthesis and defects in seven of them cause porphyria. Four of them are described as acute hepatic porphyrias, which share possible precipitation of acute attacks with symptoms engaging the nervous system. Acute intermittent porphyria (AIP), caused by partial deficiency of the porphobilinogen deaminase (PBGD), is the most frequent among hepatic porphyrias. Clinical expression is highly variable and ~ 90 % of AIP heterozygotes remain asymptomatic throughout life. During systematic genetic analysis of the AIP patients diagnosed in the Czech and Slovak Republics, we found a special case of AIP. In a 15-year-old boy with abdominal and subsequent neurological symptomatology, we identified de novo mutation 966insA within the PBGD gene leading to a stop codon after 36 completely different amino acids compared to the wt-sequence. To establish the effects of this mutation on the protein structure, we expressed mutant constructs with described mutation in E. coli and analyzed their biochemical and enzymatic properties. Moreover, computer-assisted protein structure prediction was performed.
- MeSH
- akutní intermitentní porfyrie diagnóza enzymologie genetika MeSH
- běloši MeSH
- Escherichia coli metabolismus MeSH
- hydroxymethylbilansynthasa chemie genetika izolace a purifikace MeSH
- lidé MeSH
- mladiství MeSH
- molekulární modely MeSH
- molekulární sekvence - údaje MeSH
- mutace * MeSH
- mutační analýza DNA MeSH
- rodokmen MeSH
- sekvence nukleotidů MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
- práce podpořená grantem MeSH
