No abstract

Vitamin D insufficiency/deficiency is prevalent worldwide. We investigated the effect of vitamin D intake and ultraviolet ray (UV) exposure on serum vitamin D concentration in Japan. A total of 107 healthy adult participants were recruited from Hokkaido (43 • N) and Kumamoto (33 • N) prefectures. All participants undertook surveys in both summer and winter. Serum 25-hydroxyvitamin D (25(OH)D 3 ) was examined, and vitamin D intake was assessed with a diet history questionnaire. UV exposure was measured with a wearable UV dosimeter. Regression analysis was performed to investigate the relationship between these factors, with covariates such as sun avoidance behavior. The prevalence of vitamin D insufficiency (serum 25(OH)D 3 ; 12 ng/mL (30 nmol/L) ≤ and <20 ng/mL (50 nmol/L))/deficiency (<12 ng/mL) was 47.7% in summer and 82.2% in winter. UV exposure time was short in Kumamoto (the urban area), at 11.6 min in summer and 14.9 min in winter. In Hokkaido (the rural area), UV exposure time was 58.3 min in summer and 22.5 min in winter. Vitamin D intake was significantly associated with serum 25(OH)D 3 , and a 1 µg/1000 kcal increase in intake was necessary to increase 25(OH)D 3 by 0.88 ng/mL in summer and by 1.7 ng/mL in winter. UV exposure time was significantly associated with serum 25(OH)D 3 in summer, and a 10 min increase in UV exposure time was necessary to increase 25(OH)D 3 by 0.47 ng/mL. Although consideration of personal occupation and lifestyle is necessary, most Japanese may need to increase both vitamin D intake and UV exposure.

The eukaryotic 20 S proteasome is the prototype of a new family of the N-terminal nucleophil hydrolases and is composed of numerous low molecular mass subunits arranged in a stack of four rings, each containing seven different ␣-or ␤-subunits. Among the ␤-type subunits in the yeast proteasome, three proteolytically active ones were identified, although the functions of the other ␤-and ␣-type subunits remain to be clarified. We report here that the purified 20 S proteasome exhibits intrinsic nucleoside diphosphate (NDP) kinase-like activity. The proteasome exhibited a preference for ATP and dATP as phosphate donors, and a broad specificity for NDPs, other than GDP, as phosphate acceptors, unlike conventional NDP kinase, which catalyzes the transfer of ␥-phosphate between NDPs and nucleoside triphosphates. During the transfer of ␥-phosphate, the proteasome formed acid-labile phosphohistidine as autophosphorylated intermediates, and NDP-dependent dephosphorylation of the latter then occurred. These enzymatic properties are similar to those of the molecular chaperone, Hsp70, which also exhibits intrinsic NDP kinase-like activity, instead of ATPase activity. C5 among the ␤-type subunits and C8 among the ␣-type subunits were autophosphorylated during the ␥-phosphate transfer reaction and were photoaffinity labeled with 8-azido-[␣-32 P]ATP, suggesting that the C5 and C8 subunits of the proteasome are responsible for the NDP kinase-like activity.The 20 S proteasome, representing a new family of the Ntn 1 hydrolases (1, 2), is the central enzyme in protein degradation in both the cytosol and the nucleus and plays a role in the control of cellular processes, such as metabolism, the cell cycle, the immune response (by generating antigenic peptides), and the stress response (by removing abnormal proteins) (3). Eukaryotic proteasomes have multiple proteolytic activities that have been widely referred to as trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolase activities (1-6), and mammalian proteasomes have another two activities (7). These functions are linked to ubiquitin-and ATP-requiring and to ubiquitin-independent protein degradation pathways, both of which involve the 26 S proteasome, the core and proteolytic chamber of which are formed by the 20 S proteasome. It is generally thought that the proteolytic activity of the 26 S proteasome is regulated by 19 S "cap" regulatory complexes (8, 9), which contain ATPases and serve to unfold substrate proteins prior to translocation to the proteolytic 20 S core, although direct biochemical evidence of such a chaperone-like function of the 19 S cap is lacking (3, 6). The eukaryotic 20 S proteasome consists of 28 subunits with seven different ␣ and ␤ subunits (4, 10, 11), and that in animal cells contains additional nonessential subunits that are ␥-interferon-inducible and contribute to antigen processing (12). The crystal structures of the yeast and archaebacterium Thermoplasma acidophilum proteasomes revealed that the subunits are arranged in a particle compri...

14-3-3 proteins play a role in many cellular functions as molecular chaperone and adapter proteins: they bind to and modulate several proteins involved in cell proliferation and differentiation, and also function ATP-dependently in targeting of precursors to mitochondria. We show here that 14-3-3 purified from a human lymphoblastoma and also its recombinant T isoform exhibited intrinsic nucleoside diphosphate (NDP) kinaselike activity. 14-3-3 proteins preferentially catalyzed the transfer of the y-phosphate group from ATP, dATP or dGTP to all nucleoside diphosphates and this transfer involved acid-labile phosphoenzyme intermediates. They also simultaneously catalyzed the reverse reaction of ATP hydrolysis. These properties of 14-3-3 are similar to those of NDP kinase, but not to those of adenylate kinase.© 1997 Federation of European Biochemical Societies.

Cleavage of the envelope glycoprotein precursor gp160 of HIV-1 is a prerequisite for the infectivity of HIV-1, and occurs at least in part before gp160 reaches the cell surface. Kexin/subtilisin-related endopeptidases are proposed enzyme candidates for this intracellular processing. In this study, we reveal the possibility that plasminogen binds to the cell surface and part of gp160 escaping intracellular processing is cleaved by plasmin extracellularly. Plasmin cleaves gp160 precisely at the C-terminal arginine residue of gp120, and the processing is effectively inhibited by an analogue peptide of the cleavage motif (RXK/RR) and by plasmin inhibitors.z 1999 Federation of European Biochemical Societies.