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111.
Peripheral alpha1,3-fucosylation of glycans occurs by the action of either
one of five different alpha1,3-fucosyltransferases (Fuc-Ts) cloned to date.
Fuc-TVI is one of the alpha1,3-fucosyltransferases which is capable to
synthesize selectin ligands. The major alpha1, 3- fucosyltransferase
activity in human plasma is encoded by the gene for fucosyltransferase VI,
which presumably originates from liver cells. While the sequence,
chromosomal localization, and kinetic properties of Fuc-TVI are known,
immunocytochemical localization and trafficking studies have been
impossible because of the lack of specific antibodies. Here we report on
the development and characterization of a peptide-specific polyclonal
antiserum monospecific to Fuc-TVI and an antiserum to purified soluble
recombinant Fuc-TVI crossreactive with Fuc-TIII and Fuc-TV. Both antisera
were applied for immunodetection in stably transfected CHO cells expressing
the full-length form of this enzyme (CHO clone 61/11). Fuc-TVI was found to
be a resident protein of the Golgi apparatus. In addition, more than 30% of
cell-associated and released enzyme activity was found in the medium.
Maturation and release of Fuc-TVI was analyzed in metabolically labeled CHO
61/11 cells followed by immunoprecipitation. Fuc-TVI occurred in two forms
of 47 kDa and 43 kDa bands, while the secreted form was detected as a 43
kDa. These two different intracellular forms arose by posttranslational
modification, as shown by pulse-chase experiments. Fuc-TVI was released to
the supernatant by proteolytic cleavage as a partially endo-H resistant
glycoform.
相似文献
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115.
Matthew R. McLennan 《Primates; journal of primatology》2014,55(2):173-178
Insects are a nutritious food source for many primates. In chimpanzees, insectivory is most prevalent among communities that manufacture tools to harvest social insects, particularly ants and termites. In contrast to other long-term study sites, chimpanzees (Pan troglodytes schweinfurthii) in Budongo Forest and Kibale National Park, Uganda, rarely eat insects and have small foraging tool kits, supporting speculation that infrequent insectivory—technically aided or otherwise—characterises chimpanzees in this part of Uganda’s Rift Valley. To expand the dataset for this region, insect foraging was investigated at Bulindi (25 km from Budongo) over 19 months during two studies in 2007–2008 and 2012–2013. Systematic faecal analysis demonstrated that insectivory is a habitual foraging activity at this site. Overall levels of insect consumption varied considerably across months but were not predicted by monthly changes in rainfall or fruit intake. Unlike their Budongo and Kibale counterparts, Bulindi chimpanzees often consume ants (principally weaver ants, Oecophylla longinoda) and use sticks to dig out stingless bee (Meliponini) ground nests. In other respects, however, insectivory at Bulindi conforms to the pattern observed elsewhere in this region: they do not manufacture ‘fishing’ or ‘dipping’ tools to harvest termites and aggressive or hard-to-access ants (e.g., army ants, Dorylus spp.), despite availability of suitable prey. The Bulindi data lend support to the supposition that chimpanzees in this part of the Rift Valley rarely exploit termites and Dorylus ants, apparently lacking the ‘cultural knowledge’ that would enable them to do so most efficiently (i.e., tool use). The study’s findings contribute to current debates about the relative influence of genetics, environment and culture in shaping regional and local variability in Pan foraging ecology. 相似文献
116.
Carloto A Costas MJ Cameselle JC McLennan AG Ribeiro JM 《Biochimica et biophysica acta》2006,1760(10):1545-1551
Free ADP-ribose is a putative second messenger and also a potentially toxic compound due to its non-enzymic reactivity towards protein side chains. ADP-ribose hydrolysis is catalysed by NDP-sugar/alcohol pyrophosphatases of differing specificity, including a highly specific, low-K(m) ADP-ribose pyrophosphatase. In humans, a submicromolar-K(m) ADP-ribose pyrophosphatase has been purified from placenta, while recombinant NUDT9 has been described as a similarly specific enzyme with a nudix motif, but with a 10(2)-10(3) higher K(m). Here, a comparative study of both proteins is presented showing that they are in fact enzymically indistinguishable; crucially, they both have submicromolar K(m) for ADP-ribose. This study firmly supports the view that the ADP-ribose pyrophosphatase present in human tissues is a product of the NUDT9 gene. In addition, this study reveals previously unknown properties of both enzyme forms. They display the same, differential properties in the presence of Mg(2+) or Mn(2+) as activating cations with respect to substrate specificity, ADP-ribose saturation kinetics, and inhibition by fluoride. Treatment with H(2)O(2) alters the Mg(2+)/Mn(2+) responses and increases the K(m) values for ADP-ribose, changes that are reversed by DTT. The results are discussed in relation to the proposed roles for ADP-ribose in oxidative/nitrosative stress and for ADP-ribose pyrophosphatase as a protective enzyme whose function is to limit the intracellular accumulation of ADP-ribose. 相似文献
117.
António Carloto María Jesús Costas José Carlos Cameselle Alexander G. McLennan João Meireles Ribeiro 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
Free ADP-ribose is a putative second messenger and also a potentially toxic compound due to its non-enzymic reactivity towards protein side chains. ADP-ribose hydrolysis is catalysed by NDP-sugar/alcohol pyrophosphatases of differing specificity, including a highly specific, low-Km ADP-ribose pyrophosphatase. In humans, a submicromolar-Km ADP-ribose pyrophosphatase has been purified from placenta, while recombinant NUDT9 has been described as a similarly specific enzyme with a nudix motif, but with a 102–103 higher Km. Here, a comparative study of both proteins is presented showing that they are in fact enzymically indistinguishable; crucially, they both have submicromolar Km for ADP-ribose. This study firmly supports the view that the ADP-ribose pyrophosphatase present in human tissues is a product of the NUDT9 gene. In addition, this study reveals previously unknown properties of both enzyme forms. They display the same, differential properties in the presence of Mg2+ or Mn2+ as activating cations with respect to substrate specificity, ADP-ribose saturation kinetics, and inhibition by fluoride. Treatment with H2O2 alters the Mg2+/Mn2+ responses and increases the Km values for ADP-ribose, changes that are reversed by DTT. The results are discussed in relation to the proposed roles for ADP-ribose in oxidative/nitrosative stress and for ADP-ribose pyrophosphatase as a protective enzyme whose function is to limit the intracellular accumulation of ADP-ribose. 相似文献
118.
The DR2356 nudix hydrolase gene from Deinococcus radiodurans has been cloned and the product expressed as an 18 kDa histidine-tagged protein. The enzyme hydrolysed adenosine and diadenosine polyphosphates, always generating ATP as one of the initial products. ATP and other (deoxy)nucleoside triphosphates were also substrates, yielding (d)NDP and Pi as products. The DR2356 protein was most active at pH 8.6–9.0 and showed a strong preference for Mn2+ as activating cation. Mg2+ ions at 15 mM supported only 5% of the activity achieved with 2 mM Mn2+. K
m and k
cat values for diadenosine tetra-, penta- and hexaphosphates were 2.0, 2.4 and 1.1 μM and 11.4, 28.6 and 12.0 s−1, respectively, while for GTP they were 20.3 μM and 1.8 s−1, respectively. The K
m for adenosine 5′-pentaphosphate was <1 μM. Expression analysis showed the DR2356 gene to be induced eight- to ninefold in stationary phase and in cells subjected to slow dehydration plus rehydration. Superoxide (but not peroxide) treatment and rapid dehydration caused a two-to threefold induction. The Mn-requirement and induction in stationary phase suggest that DR2356 may have a specific role in maintenance mode metabolism in stationary phase as Mn2+ accumulates. 相似文献
119.
Young AA McLennan S Smith MM Smith SM Cake MA Read RA Melrose J Sonnabend DH Flannery CR Little CB 《Arthritis research & therapy》2006,8(2):R41-6
Osteoarthritis is a disease of multifactorial aetiology characterised by progressive breakdown of articular cartilage. In the early stages of the disease, changes become apparent in the superficial zone of articular cartilage, including fibrillation and fissuring. Normally, a monolayer of lubricating molecules is adsorbed on the surface of cartilage and contributes to the minimal friction and wear properties of synovial joints. Proteoglycan 4 is the lubricating glycoprotein believed to be primarily responsible for this boundary lubrication. Here we have used an established ovine meniscectomy model of osteoarthritis, in which typical degenerative changes are observed in the operated knee joints at three months after surgery, to evaluate alterations in proteoglycan 4 expression and localisation in the early phases of the disease. In normal control joints, proteoglycan 4 was immunolocalised in the superficial zone of cartilage, particularly in those regions of the knee joint covered by a meniscus. After the onset of early osteoarthritis, we demonstrated a loss of cellular proteoglycan 4 immunostaining in degenerative articular cartilage, accompanied by a significant (p < 0.01) decrease in corresponding mRNA levels. Early loss of proteoglycan 4 from the cartilage surface in association with a decrease in its expression by superficial-zone chondrocytes might have a role in the pathogenesis of osteoarthritis. 相似文献
120.
JC de Mauroy HR Weiss AG Aulisa L Aulisa JI Brox J Durmala C Fusco TB Grivas J Hermus T Kotwicki G Le Blay A Lebel L Marcotte S Negrini L Neuhaus T Neuhaus P Pizzetti L Revzina B Torres PJM Van Loon E Vasiliadis M Villagrasa M Werkman M Wernicka MS Wong F Zaina 《Scoliosis》2010,5(1):1-15