Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-Acetylneuraminic acid cytidylyltransferase (EC 2.7.7.43) (CAMP-NeuAc synthetase) from rat liver catalyzes the formation of cytidine monophosphate N-acetylneuraminic acid from CTP and NeuAc. We have purified this enzyme to apparent homogeneity (241-fold) using gel filtration on Sephacryl S-200 and two types of affinity chromatographies (Reactive Brown-10 Agarose and Blue Sepharose CL-6B columns). The pure enzyme, whose amino acid composition and NH2-terminal amino acid sequence are also established, migrates as a single protein band on non-denaturing polyacrylamide gel electrophoresis. The molecular mass of the native enzyme, estimated by gel filtration, was 116 +/- 2 kDa whereas its Mr in sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 58 +/- 1 kDa. CMP-NeuAc synthetase requires Mg2+ for catalysis although this ion can be replaced by Mn2+, Ca2+, or Co2+. The optimal pH was 8.0 in the presence of 10 mM Mg2+ and 5 mM dithiothreitol. The apparent Km for CTP and NeuAc are 1.5 and 1.3 mM, respectively. The enzyme also converts N-glycolylneuraminic acid to its corresponding CMP-sialic acid (Km, 2.6 mM), whereas CMP-NeuAc, high CTP concentrations, and other nucleotides (CDP, CMP, ATP, UTP, GTP, and TTP) inhibited the enzyme to different extents.
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PMID:Purification and characterization of the nuclear cytidine 5'-monophosphate N-acetylneuraminic acid synthetase from rat liver. 157 59

The P2Y2 receptor is a uridine/adenosine triphosphate (UTP/ATP)-sensitive G-protein-linked nucleotide receptor that previously has been reported to stimulate the phosphoinositide signaling pathway. Messenger RNA for this receptor has been detected in brain tissue. We have investigated the coupling of the molecularly defined rat P2Y2 receptor to neuronal N-type Ca2+ channels and to M-type K+ channels by heterologous expression in rat superior cervical sympathetic (SCG) neurons. After the injection of P2Y2 cRNA, UTP inhibited the currents carried by both types of ion channel. As previously reported [Filippov AK, Webb TE, Barnard EA, Brown DA (1997) Inhibition by heterologously expressed P2Y2 nuerones. Br J Pharmacol 121:849-851], UTP inhibited the Ca2+ current (ICa(N)) by up to 64%, with an IC50 of approximately 0.5 microM. We now find that UTP also inhibited the K+M current (IK(M)) by up to 61%, with an IC50 of approximately 1.5 microM. UTP had no effect on either current in neurons not injected with P2Y2 cRNA. Structure-activity relations for the inhibition of ICa(N) and IK(M) in P2Y2 cRNA-injected neurons were similar, with UTP >/= ATP > ITP >> GTP,UDP. However, coupling to these two channels involved different G-proteins: pretreatment with Pertussis toxin (PTX) did not affect UTP-induced inhibition of IK(M) but reduced inhibition of ICa(N) by approximately 60% and abolished the voltage-dependent component of this inhibition. In unclamped neurons, UTP greatly facilitated depolarization-induced action potential discharges. Thus, the single P2Y2 receptor can couple to at least two G-proteins to inhibit both Ca2+N and K+M channels with near-equal facility. This implies that the P2Y2 receptor may induce a broad range of effector responses in the nervous system.
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PMID:P2Y2 nucleotide receptors expressed heterologously in sympathetic neurons inhibit both N-type Ca2+ and M-type K+ currents. 965 Dec

Brown hare is a seasonal breeding mammal and under the influence of photoperiod the spermatogenesis ceases during autumn months - most markedly in September and October. Testis samples from 34 animals, sacrificed between July and December were fixed in Bouin solution, embedded in paraffin, subjected to immunohistochemistry and analysed by light microscopy. TUNEL (terminal deoxynucleotidyl transferase-mediated d'UTP nick end labeling) method was applied to detect apoptosis, anti PCNA (proliferating cell nucleolar antigen) antibodies were used to evaluate cell proliferation and antibodies against apolipoprotein D and 3beta-HSD (3beta-hidroxysteroid dehydrogenase) to evaluate the activity of the Leydig cells. Our results show that the apoptotic processes in seminiferous epithelium are obvious in August and reach peak in September, with cell death occurring during prophase of I meiotic division. In July, and from early November onwards only occasional TUNEL positive cells can be seen. The proliferation of the germ cells continues also during phase of regression (September, October and early November). Active testosterone producing Leydig cells appear to be absent in September, whereas their activity becomes obvious in the middle of November.
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PMID:Apoptosis and proliferation in the testes of the brown hare (Lepus europaeus) under the influence of photoperiod. 1167 23

Extracellular ATP triggers changes in intracellular Ca(2+), ion channel function, and membrane trafficking in adipocytes. The aim of the present study was to determine which P2 receptors might mediate the Ca(2+) signaling and membrane trafficking responses to ATP in brown fat cells. RT-PCR was used to determine which P2 receptors are expressed in brown fat cells. Responses to nucleotide agonists and antagonists were characterized using fura-2 fluorescence imaging of Ca(2+) responses, and FM 1-43 fluorescence imaging and membrane capacitance measurements to assess membrane trafficking. The pharmacology of the Ca(2+) responses fits the properties of the P2Y receptors for which mRNA is expressed, but the agonist and antagonist sensitivity of the membrane-trafficking response was not consistent with any P2 receptor described to date. Brown adipocytes expressed mRNA for P2Y(2), P2Y(6), and P2Y(12) metabotropic receptors and P2X(1), P2X(2), P2X(3), P2X(4), P2X(5), and P2X(7) ionotropic receptors. The agonists ATP, ADP, UTP, UDP and 2', 3'-(benzoylbenzoyl) ATP (BzATP) increased intracellular Ca(2+), while 100 microM: suramin, pyridoxal-phosphate-6-azophenyl-2' 4'-disulfonic acid (PPADS), or Reactive Blue 2 partially blocked Ca(2+) responses. ATP, but not ADP, UTP, UDP or BzATP activated membrane trafficking. The membrane response could be blocked completely with 1 microM: PPADS but not by the antagonist MRS2179. We conclude that multiple P2 receptors mediate the ATP responses of brown fat cells, and that membrane trafficking is regulated by a P2 receptor showing unusual properties.
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PMID:Differential regulation of ca(2+) signaling and membrane trafficking by multiple p2 receptors in brown adipocytes. 1655 Apr 84