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A novel signaling intermediate, SHEP1, directly couples Eph receptors to R-Ras and Rap1A

JOURNAL OF BIOLOGICAL CHEMISTRY 1999年第45期274卷 31941-31946页

作者： Dodelet, VC Pazzagli, C Zisch, AH Hauser, CA Pasquale, EB Burnham Inst La Jolla CA 92037 USA

The Eph family of receptor tyrosine kinases has been implicated in many developmental patterning processes, including cell segregation, cell migration, and axon guidance. The cellular components involved in the signaling pathways of the Eph receptors, however, are incompletely characterized. Using a yeast two-hybrid screen, we have identified a novel signaling intermediate, SHEP1 (SH2 domain-containing Eph receptor-binding protein 1), which is expressed in the embryonic and adult brain. SHEP1 contains an Src homology 2 domain that binds to a conserved tyrosine-phosphorylated motif in the juxtamembrane region of the EphB2 receptor and may itself be a target of EphB2 kinase activity, since it becomes heavily tyrosine-phosphorylated in cells expressing activated EphB2, SHEP1 also contains a domain similar to Ras guanine nucleotide exchange factor domains and binds to the GTPases R-Ras and Rap1A, but not Ha-Ras or Ra1A, Thus, SHEP1 directly links activated, tyrosine-phosphorylated Eph receptors to small Ras superfamily GTPases.

关键词：衔接蛋白质类信号转导氨基酸序列载体蛋白质类/化学载体蛋白质类/代谢细胞系克隆分子 GTP磷酸水解酶类/代谢基因文库分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/代谢聚合酶链反应受体蛋白质酪氨酸激酶类/代谢受体 EphB2 信号传导 rap1GTP结合蛋白质类/代谢 ras蛋白质类/代谢动物人类小鼠兔

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Characterization of four mammalian numb protein isoforms - Identification of cytoplasmic and membrane-associated variants of the phosphotyrosine binding domain

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JOURNAL OF BIOLOGICAL CHEMISTRY 1999年第46期274卷 33097-33104页

作者： Dho, SE French, MB Woods, SA McGlade, CJ Hosp Sick Children Arthur & Sonia Labatt Brain Tumour Res Ctr Toronto ON M5G 1X8 Canada Univ Toronto Dept Med Biophys Toronto ON M5G 1X8 Canada

Numb is a membrane-associated, phosphotyrosine binding (PTB) domain containing protein that functions as an intrinsic determinant of cell fate during Drosophila development. We have identified four isoforms of mammalian Numb with predicted molecular masses of 65, 66, 71, and 72 kDa that are generated by alternative splicing of the Numb mRNA. The different isoforms result from the presence of two sequence inserts within the PTB domain and the central region of the protein. The endogenous expression pattern of these isoforms, examined using specific antisera, varied in different tissues and cell lines, In addition, differentiation of P19 cells with retinoic acid leads to the specific loss of expression of the 71- and 72-kDa Numb proteins, suggesting that the expression of certain forms of Numb protein is regulated in a cell type-specific manner. Expression of Numb proteins fused to green fluorescent protein revealed that the form of the PTB domain with the alternatively spliced insert constitutively associated with the plasma membrane in polarized Madin-Darby canine kidney cells. In contrast, the isoform without the insert was cytoplasmic, suggesting that different PTB domain isoforms may regulate the subcellular localization of Numb proteins. The membrane localization may be due, in part, to differential affinity for acidic phospholipids. The distinct expression and localization patterns of the different mammalian Numb isoforms suggest that they have distinct functional properties.

关键词：氨基酸序列载体蛋白质类/代谢细胞分化/药物作用细胞系细胞膜/代谢克隆分子基因表达调控绿色荧光蛋白质类免疫印迹法发光蛋白质类膜蛋白质类/化学膜蛋白质类/遗传学显微镜检查荧光分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/遗传学磷脂类/代谢磷酸酪氨酸/代谢蛋白质结合蛋白质亚型重组融合蛋白质类维甲酸/药理学泛素蛋白连接酶类动物狗小鼠

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MDC-L, a novel metalloprotease disintegrin cysteine-rich protein family member expressed by human lymphocytes

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JOURNAL OF BIOLOGICAL CHEMISTRY 1999年第41期274卷 29251-29259页

作者： Roberts, CM Tani, PH Bridges, LC Laszik, Z Bowditch, RD Univ Oklahoma Hlth Sci Ctr Dept Biochem & Mol Biol Oklahoma City OK 73190 USA Univ Oklahoma Hlth Sci Ctr Dept Pathol Oklahoma City OK 73190 USA

The metalloprotease disintegrin cysteine-rich (MDC) proteins are a recently identified family of transmembrane proteins that function in proteolytic processing of cell surface molecules and in cell adhesion, Since lymphocytes must interact with a constantly changing environment, we hypothesized that lymphocytes would express unique MDC proteins. To identify MDC proteins expressed in human lymph node, a polymerase chain reaction-based strategy combined with degenerate oligonucleotide primers was employed, We report here the identification of MDC-L (ADAM 23), a novel member of the MDC protein family, The results obtained from cDNA cloning and Northern blot analysis of mRNA isolated from various lymphoid tissues indicate that a 2.8-kilobase mRNA encoding a transmembrane form, MDC-Lm, and a 2.2-kilobase mRNA encoding a secreted form, MDC-Ls, are expressed in a tissue-specific manner. MDC-L mRNA was shown to be predominantly expressed in secondary lymphoid tissues, such as lymph node, spleen, small intestine, stomach, colon, appendix, and trachea. Furthermore, immunohistochemical staining with an anti-MDC-L antibody demonstrated that cells with typical lymphocyte morphology are responsible for expression of the MDC-L antigen in these lymphoid tissues. MDC-Lm was found to be expressed on the surface of human peripheral blood lymphocytes and transformed B- and T-lymphocyte cell lines as an 87-kDa protein, Thus, we have identified a novel lymphocyte-expressed MDC protein family member.

关键词： ADAM蛋白质类氨基酸序列碱基序列克隆分子分解素类免疫组织化学淋巴结淋巴细胞金属内肽酶类/化学金属内肽酶类/遗传学分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/遗传学 RNA 信使/代谢序列比对人类

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A novel H⁺-coupled oligopeptide transporter (OPT3) from Caenorhabditis elegans with a predominant function as a H⁺ channel and an exclusive expression in neurons

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JOURNAL OF BIOLOGICAL CHEMISTRY 2000年第13期275卷 9563-9571页

作者： Fei, YJ Romero, MF Krause, M Liu, JC Huang, W Ganapathy, V Leibach, FH Med Coll Georgia Dept Biochem & Mol Biol Augusta GA 30912 USA Case Western Reserve Univ Dept Physiol & Biophys Sch Med Cleveland OH 44106 USA NIDDK Mol Biol Lab NIH Bethesda MD 20892 USA

We have cloned and functionally characterized a novel, neuron-specific, H+-coupled oligopeptide transporter (OPT3) from Caenorhabditis elegans that functions predominantly as a H+ channel. The opt3 gene is similar to 4.4 kilobases long and consists of 13 exons. The cDNA codes for a protein of 701 amino acids with 11 putative transmembrane domains. When expressed in mammalian cells and in Xenopus laevis oocytes, OPT3 cDNA induces H+-coupled transport of the dipeptide glycylsarcosine, Electrophysiological studies of the transport function of OPT3 in Xenopus oocytes show that this transporter, although capable of mediating H+-coupled peptide transport, functions predominantly as a H+ channel. The H+ channel activity of OPT3 is similar to 3-4-fold greater than the H+/peptide cotransport activity as determined by measurements of H+ gradient-induced inward currents in the absence and presence of the dipeptide using the two-microelectrode voltage clamp technique, A downhill influx of H+ was accompanied by a large intracellular acidification as evidenced from the changes in intracellular pH using an ion-selective microelectrode. The H+ channel activity exhibits a K-0.5(H) of 1.0 mu M at a membrane potential of -50 mV. At the level of primary structure, OPT3 has moderate homology with OPT1 and OPT2, two other Hf-coupled oligopeptide transporters previously cloned from C. elegans, Expression studies using the opt3::gfp fusion constructs in transgenic C. elegans demonstrate that opt3 gene is exclusively expressed in neurons. OPT3 may play an important physiological role as a pH balancer in the maintenance of H+ homeostasis in C. elegans.

关键词：酸类氨基酸序列碱基序列秀丽新小杆线虫/代谢漂亮新小杆线虫蛋白质类载体蛋白质类/化学载体蛋白质类/遗传学载体蛋白质类/代谢克隆分子 DNA引物基因表达调控氢离子浓度离子通道/代谢动力学分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/遗传学神经组织蛋白质类/代谢神经元/代谢肽类/代谢质子协同转运子光滑爪蟾动物

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Identification of a novel, dendritic cell-associated molecule, dectin-1, by subtractive cDNA cloning

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JOURNAL OF BIOLOGICAL CHEMISTRY 2000年第26期275卷 20157-20167页

作者： Ariizumi, K Shen, GL Shikano, S Xu, S Ritter, R Kumamoto, T Edelbaum, D Morita, A Bergstresser, PR Takashima, A Univ Texas SW Med Ctr Dept Dermatol Dallas TX 75235 USA

Dendritic cells (DC) are special subsets of antigen presenting cells characterized by their potent capacity to activate immunologically naive T cells. By subtracting the mRNAs expressed by the mouse epidermus-derived DC line XS52 with the mRNAs expressed by the J774 macrophage line, we identified five novel genes that were expressed selectively by this DC line. One of these genes encoded a type II membrane-integrated polypeptide of 244 amino acids containing a putative carbohydrate recognition domain motif at the COOH-terminal end. This molecule, termed "dectin-1," was expressed abundantly at both mRNA and protein levels by the XS52 DC line, but not by non-DC lines (including the J774 macrophage line). Dectin-1 mRNA was detected predominantly in spleen and thymus (by Northern blotting) and in skin-resident DC, i.e. Langerhans cells (by reverse transcription-polymerase chain reaction). Affinity-purified antibody against dectin-1 identified a 43-kDa glycoprotein in membrane fractions isolated from the XS52 DC line and from the dectin-1 cDNA-transfected COS-1 cells. His-tagged recombinant proteins containing the extracellular domains of dectin-1 showed marked and specific binding to the surface of T cells and promoted their proliferation in the presence of anti-CD3 monoclonal antibody at suboptimal concentrations. These in vitro results suggest that dectin-1 on DC may bind to as yet undefined ligand(s) on T cells, thereby delivering T cell co-stimulatory signals. Not only do these results document the efficacy of subtractive cDNA cloning for the identification of unique genes expressed by DC, they also provide a framework for studying the physiological function of dectin-1.

关键词：氨基酸序列印迹法 RNA COS细胞细胞培养技术/方法细胞系细胞膜/代谢克隆分子 DNA 互补/代谢树突细胞/代谢上皮细胞/代谢流式细胞术免疫印迹法外源凝集素类/代谢膜蛋白质类/化学膜蛋白质类/遗传学小鼠近交BALBC 分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/遗传学表型重组融合蛋白质类/代谢逆转录聚合酶链反应序列同源性氨基酸 T淋巴细胞/代谢组织分布动物女(雌)性小鼠兔

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Three isoforms of synaptic scaffolding molecule and their characterization -: Multimerization between the isoforms and their interaction with N-methyl-D-aspartate receptors and SAP90/PSD-95-associated protein

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JOURNAL OF BIOLOGICAL CHEMISTRY 2000年第4期275卷 2966-2972页

作者： Hirao, K Hata, Y Yao, I Deguchi, M Kawabe, H Mizoguchi, A Takai, Y JCR Pharmaceut Co Ltd Japan Sci & Technol Corp ERATO Takai Biotimer ProjectNishi Ku Kobe Hyogo 6512241 Japan Tokyo Med & Dent Univ Dept Med Biochem Bunkyo Ku Tokyo 1138519 Japan Osaka Univ Grad Sch Med Fac Med Dept Mol Biol & Biochem Suita Osaka 5650871 Japan Kyoto Univ Grad Sch Dept Anat & Neurobiol Kyoto 6068315 Japan

The synaptic scaffolding molecule (S-SCAM) has been identified as a protein interacting with SAP90/PSD-95-associated protein (SAPAP) (also called guanylate kinase-associated protein/hDLG-associated protein). S-SCAM;I has six PDZ (we have numbered them PDZ-0 to -5), two WV, and one guanylate kinase (GK) domains and interacts with N-methyl-D-aspartate (NMDA) receptor via PDZ-5 and SAPAP via the GIC domain. me have identified here shorter isoforms of S-SCAM that start at the 164th or 224th methionine, and we renamed the original one, S-SCAM alpha, the middle one, S-SCAM beta, and the shortest one, SSCAM-gamma. S-SCAM beta and -gamma have five PDZ (PDZ-1 to -5), two WW, and one GK domains. S-SCAM alpha interacted with S-SCAM beta and -gamma through the region containing PDZ-4 and -5. The region containing both of PDZ-4 and -5 is sufficient for the clustering of NMDA receptors and forms a dimer in gel filtration, suggesting that S-SCAM forms multimers via the interaction between the C-terminal PDZ domains and assembles NMDA receptors into clusters. S-SCAM beta P and -gamma also interacted with SAPAP, suggesting that the N-terminal region of the GH domain is not necessary for the interaction. Finally, we have identified the interaction of the PDZ domains of S-SCAM with the GK domain of PSD-95/SAP90. S-SCAM PSD-95/SAP90, and SAPAP are colocalized at least in some part in brain. Therefore, S-SCAM, PSD-95/SAP90, and SA-PAP may form a complex in vivo.

关键词：衔接蛋白质类信号转导氨基酸序列碱基序列生物聚合物 CHO细胞 COS细胞载体蛋白质类/化学载体蛋白质类/代谢小脑/代谢色谱法凝胶仓鼠亚科 DNA引物显微镜检查荧光分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/代谢蛋白质结合蛋白质亚型/化学蛋白质亚型/代谢受体 N-甲基-D-天冬氨酸/代谢视网膜/代谢序列同源性氨基酸动物大鼠

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Synaptic targeting of the postsynaptic density protein PSD-95 mediated by a tyrosine-based trafficking signal

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JOURNAL OF BIOLOGICAL CHEMISTRY 2000年第26期275卷 20045-20051页

作者： Craven, SE Bredt, DS Univ Calif San Francisco Sch Med Dept Physiol San Francisco CA 94143 USA Univ Calif San Francisco Program Neurosci San Francisco CA 94143 USA

Synaptic function requires proper localization of proteins at synaptic sites. Targeting of the postsynaptic density protein 95 (PSD-95) relies on multiple signals within the protein, including twelve C-terminal amino acids. We now show that this C-terminal targeting domain of PSD-95 mediates postsynaptic localization through a short tyrosine-based motif followed by a pair of hydrophobic amino acids. Consistent with a role in cellular trafficking, the tyrosine motif resembles the canonical motif for interactions with clathrin adaptor proteins. In fact, we find that the C-terminal targeting domain of PSD-95 is sufficient to mediate clathrin-dependent endocytosis when appended to a transmembrane protein. Furthermore, systematic mutagenesis reveals that endocytosis mediated by this domain depends on both the tyrosine motif and the dihydrophobic amino acid pair. Thus, postsynaptic targeting of PSD-95 requires a tyrosine-based signal that can mediate clathrin-coated vesicle formation.

关键词：氨基酸序列氨基酸类/代谢 COS细胞细胞膜/代谢细胞培养的网格蛋白/代谢保守序列 DNA 互补/代谢胞吞作用荧光抗体技术基因显性绿色荧光蛋白质类海马/胚胎学海马/代谢细胞内信号肽和蛋白质类发光蛋白质类/代谢膜蛋白质类分子序列数据诱变神经组织蛋白质类/化学神经组织蛋白质类/遗传学神经组织蛋白质类/代谢神经元/代谢蛋白质结构三级重组融合蛋白质类/化学重组融合蛋白质类/代谢信号传导突触/化学突触/代谢转染酪氨酸/化学动物大鼠

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Syne-1, a dystrophin- and klarsicht-related protein associated with synaptic nuclei at the neuromuscular junction

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JOURNAL OF BIOLOGICAL CHEMISTRY 2000年第41期275卷 31986-31995页

作者： Apel, ED Lewis, RM Grady, RM Sanes, JR Washington Univ Sch Med Dept Anat & Neurobiol St Louis MO 63110 USA Washington Univ Sch Med Dept Pediat St Louis MO 63110 USA

We describe a novel protein, Syne-1, that is associated with nuclear envelopes in skeletal, cardiac, and smooth muscle cells. Syne-1 contains multiple spectrin repeats similar to those found in dystrophin and utrophin, as well as a domain homologous to the carboxyl-terminal of Klarsicht, a protein associated with nuclei and required for a subset of nuclear migrations in Drosophila. In adult skeletal muscle fibers, levels of Syne-1 are highest in the nuclei that lie beneath the postsynaptic membrane at: the neuromuscular junction. These nuclei are transcriptionally specialized, expressing genes for synaptic components at higher levels than extrasynaptic nuclei in the same cytoplasm. Syne-1 is the first protein found to be selectively associated with synaptic nuclei. Syne-1 becomes concentrated in synaptic nuclei postnatally. It remains synaptically enriched following denervation or degeneration/regeneration, and is also present at high levels in the central nuclei of dystrophic myotubes. The location and structure of Syne-1 suggest that it may participate in the migration of myonuclei in myotubes and/or their anchoring at the postsynaptic apparatus. Finally, we identify a homologous gene, syne-2, that is expressed in an overlapping but distinct pattern.

关键词：选择性剪接/遗传学氨基酸序列细胞系果蝇蛋白质类肌营养不良蛋白/化学荧光抗体技术基因表达谱昆虫蛋白质类/化学膜转运蛋白质类微丝蛋白质类分子序列数据肌纤维骨骼/细胞学肌纤维骨骼/代谢肌蛋白质类/化学肌蛋白质类/遗传学肌蛋白质类/代谢神经组织蛋白质类/化学神经组织蛋白质类/遗传学神经组织蛋白质类/代谢神经肌肉接头/化学神经肌肉接头/细胞学神经肌肉接头/代谢核被膜/化学核蛋白质类/化学核蛋白质类/遗传学核蛋白质类/代谢沉淀素试验蛋白质结合蛋白质亚型/化学蛋白质亚型/遗传学蛋白质亚型/代谢 RNA 信使/遗传学 RNA 信使/代谢受体蛋白质酪氨酸激酶类/化学受体蛋白质酪氨酸激酶类/遗传学受体蛋白质酪氨酸激酶类/代谢受体胆碱能序列比对双杂交系统技术动物人类小鼠

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Both familial Parkinson's disease mutations accelerate α-synuclein aggregation

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JOURNAL OF BIOLOGICAL CHEMISTRY 1999年第14期274卷 9843-9846页

作者： Narhi, L Wood, SJ Steavenson, S Jiang, YJ Wu, GM Anafi, D Kaufman, SA Martin, F Sitney, K Denis, P Louis, JC Wypych, J Biere, AL Citron, M Amgen Inc Thousand Oaks CA 91320 USA

Parkinson's disease (PD) is a neurodegenerative disorder that is pathologically characterized by the presence of intracytoplasmic Lewy bodies, the major component of which are filaments consisting of alpha-synuclein. Two recently identified point mutations in alpha-synuclein are the only known genetic causes of PD, but their pathogenic mechanism is not understood. Here we show that both wild type and mutant alpha-synuclein form insoluble fibrillar aggregates with antiparallel beta-sheet structure upon incubation at physiological temperature in vitro. Importantly, aggregate formation is accelerated by both PD-linked mutations. Under the experimental conditions, the lag time for the formation of precipitable aggregates is about 280 h for the wild type protein, 180 h for the A30P mutant, and only 100 h for the A53T mutant protein. These data suggest that the formation of alpha-synuclein aggregates could be a critical step in PD pathogenesis, which is accelerated by the PD-linked mutations.

关键词：细胞系圆二色性克隆分子突变神经组织蛋白质类/化学神经组织蛋白质类/遗传学帕金森病/遗传学磷蛋白类/化学磷蛋白类/遗传学蛋白质构象蛋白质结构二级谱学傅里叶变换红外突触核蛋白类 α突触核蛋白人类

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Conserved phosphoprotein interaction motif is functionally interchangeable between ataxin-7 and arrestins

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BIOCHEMISTRY 2000年第23期39卷 6809-6813页

作者： Mushegian, AR Vishnivetskiy, SA Gurevich, VV Sun Hlth Res Inst Ralphy & Muriel Roberts Lab Vis Sci Sun City AZ 85351 USA

Olivopontocerebellar atrophy with retinal degeneration is a hereditary neurodegenerative disorder that belongs to the subtype II of the autosomal dominant cerebellar ataxias and is characterized by early-onset cerebellar and macular degeneration preceded by diagnostically useful tritan colorblindness. The gene mutated in the disease (SCA7) has been mapped to chromosome 3p12 13.5, and positional cloning identified the cause of the disease as CAG repeat expansion in this gene. The SCA 7 gene product, ataxin7, is an 897 amino acid protein with an expandable polyglutamine tract close to its N-terminus. No clues to ataxin-7 function have been obtained from sequence database searches. Here we report that ataxin-7 has a motif of ca, 50 amino acids, related to the phosphate-binding site of arrestins, To test the relevance of this sequence similarity, we introduced the putative ataxin-7 phosphate-binding site into visual arrestin and beta-arrestin. Both chimeric arrestins retain receptor-binding affinity and show characteristic high selectivity for phosphorylated activated forms of rhodopsin and beta-adrenergic receptor, respectively. Although the insertion of a Gly residue (absent in arrestins but present in the putative phosphate-binding site of ataxin-7) disrupts the function of visual arrestin-ataxin-7 chimera, it enhances the function of beta-arrestin-ataxin-7 chimera. Taken together, our data suggest that the arrestin-like site in the ataxin-7 sequence is a functional phosphate-binding site. The presence of the phosphate-binding site in ataxin-7 suggests that this protein may be involved in phosphorylation-dependent binding to its protein partner(s) in the cell.

关键词：氨基酸序列抑制蛋白类/化学抑制蛋白类/遗传学结合部位保守序列模型分子分子序列数据神经组织蛋白质类/化学神经组织蛋白质类/遗传学磷酸盐类/代谢磷蛋白类/遗传学磷蛋白类/代谢磷酰化重组融合蛋白质类脊髓小脑变性/遗传学动物牛人类

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