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0  structures 337  species 0  interactions 2197  sequences 120  architectures

Family: SPX (PF03105)

Summary: SPX domain

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SPX domain Provide feedback

We have named this region the SPX domain after (SYG1, Pho81 and XPR1). This 180 residue length domain is found at the amino terminus of a variety of proteins. In the yeast protein SYG1, the N-terminus directly binds to the G- protein beta subunit and inhibits transduction of the mating pheromone signal [3]. This finding suggests that all the members of this family are involved in G-protein associated signal transduction. The N-termini of several proteins involved in the regulation of phosphate transport, including the putative phosphate level sensors PHO81 P17442 from Saccharomyces cerevisiae and NUC-2 Q01317 from Neurospora crassa, are also members of this family [see 4,5]. The SPX domain of S. cerevisiae low-affinity phosphate transporters Pho87 and Pho90 auto-regulates uptake and prevents efflux. This SPX dependent inhibition is mediated by the physical interaction with Spl2 [6] NUC-2 contains several ankyrin repeats PF00023. Several members of this family are annotated as XPR1 proteins: the xenotropic and polytropic retrovirus receptor confers susceptibility to infection with murine leukaemia viruses (MLV) [1]. The similarity between SYG1, phosphate regulators and XPR1 sequences has been previously noted, as has the additional similarity to several predicted proteins, of unknown function, from Drosophila melanogaster, Arabidopsis thaliana, Caenorhabditis elegans, Schizosaccharomyces pombe, and Saccharomyces cerevisiae [1,2]. In addition, given the similarities between XPR1 and SYG1 and phosphate regulatory proteins, it has been proposed that XPR1 might be involved in G-protein associated signal transduction and may itself function as a phosphate sensor [1].

Literature references

  1. Battini JL, Rasko JE, Miller AD; , Proc Natl Acad Sci U S A 1999;96:1385-1390.: A human cell-surface receptor for xenotropic and polytropic murine leukemia viruses: possible role in G protein-coupled signal transduction. PUBMED:9990033 EPMC:9990033

  2. Tailor CS, Nouri A, Lee CG, Kozak C, Kabat D; , Proc Natl Acad Sci U S A 1999;96:927-932.: Cloning and characterization of a cell surface receptor for xenotropic and polytropic murine leukemia viruses. PUBMED:9927670 EPMC:9927670

  3. Spain BH, Koo D, Ramakrishnan M, Dzudzor B, Colicelli J; , J Biol Chem 1995;270:25435-25444.: Truncated forms of a novel yeast protein suppress the lethality of a G protein alpha subunit deficiency by interacting with the beta subunit. PUBMED:7592711 EPMC:7592711

  4. Lenburg ME, O'Shea EK; , Trends Biochem Sci 1996;21:383-387.: Signaling phosphate starvation. PUBMED:8918192 EPMC:8918192

  5. Lee M, O'Regan S, Moreau JL, Johnson AL, Johnston LH, Goding CR; , Mol Microbiol 2000;38:411-422.: Regulation of the Pcl7-Pho85 cyclin-cdk complex by Pho81. PUBMED:11069666 EPMC:11069666

  6. Hurlimann HC, Pinson B, Stadler-Waibel M, Zeeman SC, Freimoser FM;, EMBO Rep. 2009; [Epub ahead of print]: The SPX domain of the yeast low-affinity phosphate transporter Pho90 regulates transport activity. PUBMED:19590579 EPMC:19590579


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR004331

The SPX domain is named after SYG1/Pho81/XPR1 proteins. This 180 residue length domain is found at the amino terminus of a variety of proteins. In the yeast protein SYG1, the N terminus directly binds to the G- protein beta subunit and inhibits transduction of the mating pheromone signal [PUBMED:7592711] suggesting that all the members of this family are involved in G-protein associated signal transduction. The C-terminal of these proteins often have an EXS domain (INTERPRO) [PUBMED:9990033].

The N-termini of several proteins involved in the regulation of phosphate transport, including the putative phosphate level sensors PHO81 from Saccharomyces cerevisiae and NUC-2 from Neurospora crassa, are also members of this family [PUBMED:8918192, PUBMED:11069666]. NUC-2 contains several ankyrin repeats (INTERPRO).

Several members of this family are the XPR1 proteins: the xenotropic and polytropic retrovirus receptor confers susceptibility to infection with Murine leukemia virus (MLV) [PUBMED:9990033]. The similarity between SYG1, phosphate regulators and XPR1 sequences has been previously noted, as has the additional similarity to several predicted proteins, of unknown function, from Drosophila melanogaster, Arabidopsis thaliana, Caenorhabditis elegans, Schizosaccharomyces pombe, and Saccharomyces cerevisiae [PUBMED:9990033, PUBMED:9927670]. In addition, given the similarities between XPR1 and SYG1 and phosphate regulatory proteins, it has been proposed that XPR1 might be involved in G-protein associated signal transduction [PUBMED:16905115, PUBMED:18315545, PUBMED:18055586] and may itself function as a phosphate sensor [PUBMED:9990033].

Domain organisation

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Alignments

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

  Seed
(168)
Full
(2197)
Representative proteomes NCBI
(2267)
Meta
(25)
RP15
(468)
RP35
(969)
RP55
(1406)
RP75
(1617)
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Format an alignment

  Seed
(168)
Full
(2197)
Representative proteomes NCBI
(2267)
Meta
(25)
RP15
(468)
RP35
(969)
RP55
(1406)
RP75
(1617)
Alignment:
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Sequence:
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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

  Seed
(168)
Full
(2197)
Representative proteomes NCBI
(2267)
Meta
(25)
RP15
(468)
RP35
(969)
RP55
(1406)
RP75
(1617)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   Download   Download   Download   Download   Download   Download   Download  

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.

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Curation and family details

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Curation View help on the curation process

Seed source: Pfam-B_502 (release 6.5)
Previous IDs: none
Type: Domain
Author: Mifsud W, Bateman A
Number in seed: 168
Number in full: 2197
Average length of the domain: 161.90 aa
Average identity of full alignment: 18 %
Average coverage of the sequence by the domain: 28.52 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 26.9 26.9
Trusted cut-off 26.9 26.9
Noise cut-off 26.7 26.8
Model length: 275
Family (HMM) version: 14
Download: download the raw HMM for this family

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