Nucleotide sequence of the mouse<i>ypt1</i>gene encoding a<i>ras</i>-related GTP-binding protein

Wichmann, Hendrik; Disela, Christine; Haubruck, Heinz; Gallwitz, Dieter

doi:10.1093/nar/17.16.6737

Cited by 17 publications

(7 citation statements)

References 6 publications

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“…Thus, it appears reasonable to assume that the two isoforms were derived from the same gene by alternative mRNA splicing. The splicing site near the PM2 domain of Rag (threonine 42) is not unexpected, because it corresponds exactly with well conserved exon borders of ras (McGrath et al, 1983) and ARF-2 (Serventi et al, 1993), and is only 12 codons downstream of the border between exon 2 and 3 in Rab isotypes (Wichmann et al, 1989).…”

Section: Discussionmentioning

confidence: 80%

Cloning of a Novel Family of Mammalian GTP-binding Proteins (RagA, RagBs, RagB1) with Remote Similarity to the Ras-related GTPases

Schürmann¹,

Brauers²,

S³

et al. 1995

Journal of Biological Chemistry

112

109

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cDNA clones of two novel Ras-related GTP-binding proteins (RagA and RagB) were isolated from rat and human cDNA libraries. Their deduced amino acid sequences comprise four of the six known conserved GTPbinding motifs (PM1, -2, -3, G1), the remaining two (G2, G3) being strikingly different from those of the Ras family, and an unusually large C-terminal domain (100 amino acids) presumably unrelated to GTP binding. RagA and RagB differ by seven conservative amino acid substitutions (98% identity), and by 33 additional residues at the N terminus of RagB. In addition, two isoforms of RagB (RagB s and RagB l ) were found that differed only by an insertion of 28 codons between the GTP-binding motifs PM2 and PM3, apparently generated by alternative mRNA splicing. Polymerase chain reaction amplification with specific primers indicated that both long and short form of RagB transcripts were present in adrenal gland, thymus, spleen, and kidney, whereas in brain, only the long form RagB l was detected. A long splicing variant of RagA was not detected. Recombinant glutathione S-transferase (GST) fusion proteins of RagA and RagB s bound large amounts of radiolabeled GTP␥S in a specific and saturable manner. In contrast, GTP␥S binding of GST-RagB l hardly exceeded that of recombinant GST. GTP␥S bound to recombinant RagA, and RagB s was rapidly exchangeable for GTP, whereas no intrinsic GTPase activity was detected. A multiple sequence alignment indicated that RagA and RagB cannot be assigned to any of the known subfamilies of Ras-related GTPases but exhibit a 52% identity with a yeast protein (Gtr1) presumably involved in phosphate transport and/or cell growth. It is suggested that RagA and RagB are the mammalian homologues of Gtr1 and that they represent a novel subfamily of Ras-homologous GTP binding proteins.Ras-homologous GTPases constitute a large family of signal transducers that alternate between an activated, GTP-binding, and an inactivated, GDP-binding state (Hall, 1990;Bourne et al., 1990;Boguski and McCormick, 1993). These proteins represent cellular switches that are operated by GTP-exchange factors and factors stimulating their intrinsic GTPase activity. To date, five subfamilies of the Ras superfamily are known: Ras, Rho, Rab, Ran, and ARF 1 proteins. These subfamilies are not only characterized by common structural features but also by a similar function, e.g. regulation of growth (Ras) (Egan and Weinberg, 1993), cytoskeleton organization (Rho) (Aktories et al., 1992), or vesicle transport (Rab and ARF) (Novick and Brennwald, 1993;Kahn et al., 1993). All GTPases of the Ras superfamily have in common the presence of six conserved motifs involved in GTP/GDP binding, three of them as phosphate/magnesium binding sites (PM1-PM3), and the other three as guanine nucleotide binding sites (G1-G3) (Valencia et al., 1991). Therefore, the sequences of the least related GTPases comprise approximately 20 -30% identical amino acids, whereas the sequence similarity is considerably higher within subfamilies (e.g. Ͼ40% identity in...

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Section: Discussionmentioning

confidence: 80%

Cloning of a Novel Family of Mammalian GTP-binding Proteins (RagA, RagBs, RagB1) with Remote Similarity to the Ras-related GTPases

Schürmann¹,

Brauers²,

S³

et al. 1995

Journal of Biological Chemistry

112

109

View full text Add to dashboard Cite

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“…However, this insertion is believed to be generated by an additional exon rather than by mutually exclusive incorporation of a duplicated exon. The genomic organization of only four Rab genes (Rab1, Rab3A, Rab11B, and S10) has been reported so far (Wichmann et al, 1989;Baumert et al, 1993;Lai et al, 1994;Zheng et al, 1997). It remains to be established whether alternative splicing of duplicated exons occurs for other members of the Rab family.…”

Section: Generation Of Rab6a Isoforms By Alternative Splicingmentioning

confidence: 99%

“…Only limited information is available on the genomic organization of mammalian Rab genes (Wichmann et al, 1989;Baumert et al, 1993;Lai et al, 1994;Barbosa et al, 1995;Zheng et al, 1997). Based on their nucleotide sequences, however, it is likely that Rab isoforms are encoded by distinct genes.…”

Section: Introductionmentioning

confidence: 99%

Alternative Splicing of the HumanRab6AGene Generates Two Close but Functionally Different Isoforms

Échard

Opdam

Leeuw

et al. 2000

MBoC

106

119

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Analysis of the human Rab6A gene structure reveals the presence of a duplicated exon, and incorporation of either of the two exons by alternative splicing is shown to generate two Rab6 isoforms named Rab6A and Rab6A', which differ in only three amino acid residues located in regions flanking the PM3 GTP-binding domain of the proteins. These isoforms are ubiquitously expressed at similar levels, exhibit the same GTP-binding properties, and are localized to the Golgi apparatus. Overexpression of the GTP-bound mutants of Rab6A (Rab6A Q72L) or Rab6A' (Rab6A' Q72L) inhibits secretion in HeLa cells, but overexpression of Rab6A' Q72L does not induce the redistribution of Golgi proteins into the endoplasmic reticulum. This suggests that Rab6A' is not able to stimulate Golgi-to-endoplasmic reticulum retrograde transport, as described previously for Rab6A. In addition, Rab6A' interacts with two Rab6A partners, GAPCenA and "clone 1," but not with the kinesin-like protein Rabkinesin-6, a Golgi-associated Rab6A effector. Interestingly, we found that the functional differences between Rab6A and Rab6A' are contingent on one amino acid (T or A at position 87). Therefore, limited amino acid substitutions within a Rab protein introduced by alternative splicing could represent a mechanism to generate functionally different isoforms that interact with distinct sets of effectors.

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“…Bootstrapping techniques were then used to confirm the significance of the groupings obtained. The input sequences were derived from the following sources: rablb [22], rab2 and tab4 [21], tab5 [25], tab7 [4] and BRL-ras [3] from rat, canine and human cDNA libraries; ara [12] and rhal [2] fromArabidopsis thaliana, rgpl [10] from rice; and yptl [23] and ypt3 [13] from yeast.…”

Section: A T T~t G T C T a T G A~t T T T 830 840 Cttgtttggc T T G T Gmentioning

confidence: 99%

Sequence of a novel plant ras-related cDNA from Pisum sativum

1993

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A clone isolated from a purple podded pea (Pisum sativum L.) cDNA library was shown to contain the complete coding sequence of a polypeptide with considerable homology to various members of the ras superfamily. The ras superfamily are a group of monomeric GTP-binding proteins of 21-25 kDa found in eukaryotic cells. Conserved sequences in the isolated clone include the GTP-binding site, GDP/GTP hydrolysis domain and C-terminal Cys residues involved in membrane attachment. Comparisons of the predicted amino acid sequence with those of other ras proteins show significantly higher homologies (ca. 70%) to two mammalian gene products, those of the BRL-ras oncogene, and the canine rab7 gene, than to any of the plant ras gene products so far identified (< 40% homology). The high percentage of amino acid identity suggests that this cDNA may be the product of a gene, designated Psa-rab, which is the plant counterpart of rab7. Rab/ypt proteins are a subfamily of the ras superfamily thought to be involved in intracellular transport from the endoplasmic reticulum to the Golgi apparatus and in vesicular transport. Northern blot hybridisation analysis of total RNA from green and purple podded pea revealed a mRNA species of approximately the same size as the isolated cDNAs.

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Nucleotide sequence of the mouseypt1gene encoding aras-related GTP-binding protein

Cited by 17 publications

References 6 publications

Cloning of a Novel Family of Mammalian GTP-binding Proteins (RagA, RagBs, RagB1) with Remote Similarity to the Ras-related GTPases

Cloning of a Novel Family of Mammalian GTP-binding Proteins (RagA, RagBs, RagB1) with Remote Similarity to the Ras-related GTPases

Alternative Splicing of the HumanRab6AGene Generates Two Close but Functionally Different Isoforms

Sequence of a novel plant ras-related cDNA from Pisum sativum

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