The TITAN5 Gene of Arabidopsis Encodes a Protein Related to the ADP Ribosylation Factor Family of GTP Binding Proteins

McElver, John; Patton, David R.; Rumbaugh, Michael; Liu, Chunming; Li, Yang; Meinke, David W.

doi:10.2307/3871137

Cited by 21 publications

(36 citation statements)

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“…T-DNA insertional mutant plants were identified according to a PCR-based method as described previously (Krysan et al 1999;McElver et al 2000). The pakrp1-1 line was isolated from the mutant pool at the Arabidopsis Knockout Facility at the University of Wisconsin Biotechnology Center.…”

Section: Isolation Of T-dna Insertional Mutationsmentioning

confidence: 99%

Localization of two homologous Arabidopsis kinesin-related proteins in the phragmoplast

Pan

Lee

Liu

2004

Planta

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During plant cytokinesis, kinesin-related motor proteins are believed to play critical roles in microtubule organization and vesicle transport in the phragmoplast. Previously, we reported that the motor AtPAKRP1 was associated with the plus end of phragmoplast microtubules in Arabidopsis thaliana [Lee Y-RJ, Liu B (2000) Curr Biol 10:797-800]. In this paper, we report a full-length cDNA from the same organism, which encodes a polypeptide 74% identical to AtPAKRP1. This AtPAKRP1-like protein--AtPAKRP1L--and AtPAKRP1 share similar domain structures along the polypeptides. Peptide antibodies were raised and purified to distinguish the two polypeptides in vitro and in vivo. When monospecific anti-AtPAKRP1 and anti-AtPAKRP1L antibodies were used in immunofluorescence, they both decorated the plus end of phragmoplast microtubules at all stages of phragmoplast development. Their localization patterns were indistinguishable from each other. By using bacterially expressed fusion proteins of motor-less versions of both polypeptides, it was revealed that AtPAKRP1 and AtPAKRP1L were able to interact with themselves and with each other. Using T-DNA insertional mutants, it was also demonstrated that AtPAKRP1 and AtPAKRP1L were not required for each other's localization. Our results therefore indicate that AtPAKRP1 and AtPAKRP1L are both expressed in the same cells, and likely have identical functions in the phragmoplast by forming either homodimers or heterodimers.

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Section: Isolation Of T-dna Insertional Mutationsmentioning

confidence: 99%

Localization of two homologous Arabidopsis kinesin-related proteins in the phragmoplast

Pan

Lee

Liu

2004

Planta

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“…Arl2 modulates the tubulin-GAP activity of cofactors C and D (22), and mutations in its putative yeast homologs affect microtubule stability (11,12,23). Mutations in Arl2 in Arabidopsis thaliana also result in the loss of microtubules (24,25). Given the sequence similarity between cofactor C and RP2 and the interaction of Arl2 with tubulin-folding cofactors, we decided to compare the functional and biochemical properties of RP2 and cofactor C and to investigate the possibility that RP2 might interact with one or more Arl proteins.…”

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confidence: 99%

Functional Overlap between Retinitis Pigmentosa 2 Protein and the Tubulin-specific Chaperone Cofactor C

Bartolini¹,

Bhamidipati²,

Thomas³

et al. 2002

Journal of Biological Chemistry

101

102

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Mutations in the X-linked retinitis pigmentosa 2 gene cause progressive degeneration of photoreceptor cells. The retinitis pigmentosa 2 protein (RP2) is similar in sequence to the tubulin-specific chaperone cofactor C. Together with cofactors D and E, cofactor C stimulates the GTPase activity of native tubulin, a reaction regulated by ADP-ribosylation factor-like 2 protein. Here we show that in the presence of cofactor D, RP2 protein also stimulates the GTPase activity of tubulin. We find that this function is abolished by mutation in an arginine residue that is conserved in both cofactor C and RP2. Notably, mutations that alter this arginine codon cause familial retinitis pigmentosa. Our data imply that this residue acts as an "arginine finger" to trigger the tubulin GTPase activity and suggest that loss of this function in RP2 contributes to retinal degeneration. We also show that in Saccharomyces cerevisiae, both cofactor C and RP2 partially complement the microtubule phenotype resulting from deletion of the cofactor C homolog, demonstrating their functional overlap in vivo. Finally, we find that RP2 interacts with GTP-bound ADP ribosylation factor-like 3 protein, providing a link between RP2 and several retinal-specific proteins, mutations in which also cause retinitis pigmentosa.Retinitis pigmentosa is a degenerative disease and the major cause of heritable blindness (1). It is caused by mutations in a dizzying variety of genes; some are structural proteins of photoreceptors, many are involved in photoreception and transduction, and a few are seemingly unrelated ubiquitously expressed proteins (see RetNet, www.sph.uth.tmc.edu/retnet/). Most (80 -90%) cases of X-linked retinitis pigmentosa are caused by mutations in two genes, XRP2 and XRP3 (2). These were isolated by positional cloning and shown to encode, respectively, the RP2 1 protein (3) and the retinitis pigmentosa GTPase regulator (RP3) (4, 5). The function of RP2 is unknown, and the gene is expressed at a low level in all tissues examined; it is targeted to the plasma membrane by myristoylation and palmitoylation of its amino terminus (6).RP2 has amino acid sequence similarity over half of its length to the tubulin-specific chaperone protein cofactor C (3). It has been shown that cofactor C acts in a pathway together with four other tubulin-specific chaperone proteins (cofactors A, B, D, and E) to chaperone quasi-native ␣-and ␤-tubulin subunits released from the cytosolic chaperonin CCT and assemble the ␣/␤-tubulin heterodimer. Each step in this pathway has been deduced from in vitro reconstitution experiments using purified components (7-9). The pathway hinges on the formation of a supercomplex containing ␣Ϫ and ␤-tubulin and cofactors C, D, and E. The hydrolysis of GTP by tubulin, stimulated by cofactors C and D, is part of the heterodimer assembly reaction; the stimulated hydrolysis of GTP by ␤-tubulin acts as a switch for the release from the supercomplex of native, newly made tubulin heterodimers (10). Cofactor C and D in combination have also b...

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“…R1C4, in the "Cellular transport and transport mechanisms" group, encodes ADP-ribosylation factor (ARF). The ARF proteins are members of the RAS family of small GTP-binding proteins that regulate various cellular functions in eukaryotes, such as vesicle formation and intracellular vesicle transport (McElver et al 2000). This gene was also identified as a defense-related rice gene in a previous report (Xiong et al 2001).…”

Section: Discussionmentioning

confidence: 96%

Isolation and characterization of novel defense response genes involved in compatible and incompatible interactions between rice and Magnaporthe grisea

Jantasuriyarat

Zhou

et al. 2003

Theor Appl Genet

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To identify early-induced defense genes involved in broad-spectrum resistance to rice blast, suppression subtractive hybridization was used to generate two cDNA libraries enriched for transcripts differentially expressed in Pi9(t)-resistant and -susceptible plants. After differential screening by membrane-based hybridization and subsequent confirmation by reverse Northern blot analysis, selected clones were sequenced and analyzed. Forty-seven unique cDNA clones were found and assigned to eight different groups according to the putative function of their homologous genes in the database. These genes may be involved in pathogen or stress response, signal transduction, transcription, cell transport, metabolism, energy or protein destination. Northern blot analysis showed that most of these genes were induced or suppressed after blast infection, and that half of them showed differential expression patterns between compatible and incompatible interactions. Interestingly, all but one of the identified genes are reported here for the first time to be involved in defense response to rice blast. In addition, hybridization of these clones with cDNAs synthesized from RNA samples from bacterial blight-infected leaves showed that few of them are induced or repressed in Xa21- or Xa7-resistant plants, suggesting a minimum overlap of defense responses mediated by different resistance genes to fungal and bacterial pathogens at an early stage of infection. Further characterization and functional analysis of these genes will enhance our understanding of the molecular mechanism of broad-spectrum resistance in rice.

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The TITAN5 Gene of Arabidopsis Encodes a Protein Related to the ADP Ribosylation Factor Family of GTP Binding Proteins

Cited by 21 publications

References 0 publications

Localization of two homologous Arabidopsis kinesin-related proteins in the phragmoplast

Localization of two homologous Arabidopsis kinesin-related proteins in the phragmoplast

Functional Overlap between Retinitis Pigmentosa 2 Protein and the Tubulin-specific Chaperone Cofactor C

Isolation and characterization of novel defense response genes involved in compatible and incompatible interactions between rice and Magnaporthe grisea

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