INPP5B inositol polyphosphate-5-phosphatase B [Homo sapiens (human)] - Gene

Summary

Official Symbol: INPP5Bprovided by HGNC
Official Full Name: inositol polyphosphate-5-phosphatase Bprovided by HGNC
Primary source: HGNC:HGNC:6077
See related: Ensembl:ENSG00000204084 MIM:147264; AllianceGenome:HGNC:6077
Gene type: protein coding
RefSeq status: REVIEWED
Organism: Homo sapiens
Lineage: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo
Also known as: 5PTase
Summary: This gene encodes a member of a family of inositol polyphosphate-5-phosphatases. These enzymes function in the regulation of calcium signaling by inactivating inositol phosphates. The encoded protein is localized to the cytosol and mitochondria, and associates with membranes through an isoprenyl modification near the C-terminus. Alternatively spliced transcript variants of this gene have been described. [provided by RefSeq, Jul 2014]
Expression: Ubiquitous expression in lymph node (RPKM 6.6), ovary (RPKM 6.5) and 25 other tissues See more
Orthologs: mouse all
NEW: Try the new Gene table
Try the new Transcript table

Genomic context

Location:: 1p34.3

Exon count:: 33

Annotation release	Status	Assembly	Chr	Location
RS_2024_08	current	GRCh38.p14 (GCF_000001405.40)	1	NC_000001.11 (37860697..37947057, complement)
RS_2024_08	current	T2T-CHM13v2.0 (GCF_009914755.1)	1	NC_060925.1 (37727581..37813950, complement)
RS_2024_09	previous assembly	GRCh37.p13 (GCF_000001405.25)	1	NC_000001.10 (38326369..38412729, complement)

Chromosome 1 - NC_000001.11 Genomic Context describing neighboring genes

Genomic regions, transcripts, and products

Go to the top of the page Help

Go to reference sequence details

Genomic Sequence:

Go to nucleotide: Graphics FASTA GenBank

Expression

Go to the top of the page Help

See details

Project title: HPA RNA-seq normal tissues
Description: RNA-seq was performed of tissue samples from 95 human individuals representing 27 different tissues in order to determine tissue-specificity of all protein-coding genes
BioProject: PRJEB4337
Publication: PMID 24309898
Analysis date: Wed Apr 4 07:08:55 2018

Bibliography

Go to the top of the page Help

GeneRIFs: Gene References Into Functions

What's a GeneRIF?

The inositol 5-phosphatase INPP5B regulates B cell receptor clustering and signaling.
Title: The inositol 5-phosphatase INPP5B regulates B cell receptor clustering and signaling.
OCRL-mutated fibroblasts from patients with Dent-2 disease exhibit INPP5B-independent phenotypic variability relatively to Lowe syndrome cells
Title: OCRL-mutated fibroblasts from patients with Dent-2 disease exhibit INPP5B-independent phenotypic variability relatively to Lowe syndrome cells.
The crystal structures of human INPP5B in complex with phosphoinositide substrate analogs revealed a membrane interaction patch likely to assist in sequestering substrates from the lipid bilayer.
Title: Structural basis for phosphoinositide substrate recognition, catalysis, and membrane interactions in human inositol polyphosphate 5-phosphatases.
study found mouse Inpp5b and human INPP5B differ in their transcription, splicing and amino acid sequence; observations form foundation for analyzing the functional basis for the difference in how Inpp5b and INPP5B compensate for loss of Ocrl function
Title: Species-specific difference in expression and splice-site choice in Inpp5b, an inositol polyphosphate 5-phosphatase paralogous to the enzyme deficient in Lowe Syndrome.
Observational study and genome-wide association study of gene-disease association. (HuGE Navigator)
Title: Novel association strategy with copy number variation for identifying new risk Loci of human diseases.
The homologous phosphatase Inpp5b was unable to complement the Ocrl1-dependent cell migration defect.
Title: Lowe syndrome patient fibroblasts display Ocrl1-specific cell migration defects that cannot be rescued by the homologous Inpp5b phosphatase.
The NH2-terminal region of OCRL, but not of INPP5B, binds clathrin heavy chain.
Title: A PH domain within OCRL bridges clathrin-mediated membrane trafficking to phosphoinositide metabolism.
INPP5B is also localised to the early secretory pathway including the Golgi apparatus and ER-to-Golgi intermediate compartment (ERGIC).
Title: Targeting of the type II inositol polyphosphate 5-phosphatase INPP5B to the early secretory pathway.

Submit: New GeneRIF Correction

Phenotypes

Go to the top of the page Help

Find tests for this gene in the NIH Genetic Testing Registry (GTR)

Review eQTL and phenotype association data in this region using PheGenI

EBI GWAS Catalog

Description
Genetics of rheumatoid arthritis contributes to biology and drug discovery. EBI GWAS Catalog EBI GWAS CatalogPubMed

Variation

Go to the top of the page Help

See variants in ClinVar

See studies and variants in dbVar

See Variation Viewer (GRCh37.p13)

See Variation Viewer (GRCh38)

Interactions

Go to the top of the page Help

Products	Interactant	Other Gene	Complex	Source	Pubs	Description

General gene information

Go to the top of the page Help

Markers

RH120883 (e-PCR)
- UniSTS:47878

G27427 (e-PCR)
- UniSTS:62984

GDB:434012 (e-PCR)
- UniSTS:157204

D8S2279 (e-PCR)
- UniSTS:473907

D8S2282 (e-PCR)
- UniSTS:473910

D15S1477 (e-PCR)
- UniSTS:474482

D1S1423 (e-PCR)
- UniSTS:149619

D1S1425 (e-PCR)
- UniSTS:149621

STS-AA022685 (e-PCR)
- UniSTS:26489

D3S1673 (e-PCR)
- UniSTS:148450

Gene Ontology Provided by GOA

Function	Evidence Code	Pubs
enables inositol-1,3,4,5-tetrakisphosphate 5-phosphatase activity	TAS Traceable Author Statement more info
enables inositol-1,4,5-trisphosphate 5-phosphatase activity	IBA Inferred from Biological aspect of Ancestor more info
enables inositol-1,4,5-trisphosphate 5-phosphatase activity	IDA Inferred from Direct Assay more info	PubMed
enables inositol-1,4,5-trisphosphate 5-phosphatase activity	TAS Traceable Author Statement more info
enables metal ion binding	IEA Inferred from Electronic Annotation more info
enables phosphatidylinositol-4,5-bisphosphate 5-phosphatase activity	IBA Inferred from Biological aspect of Ancestor more info
enables phosphatidylinositol-4,5-bisphosphate 5-phosphatase activity	IDA Inferred from Direct Assay more info	PubMed
enables protein binding	IPI Inferred from Physical Interaction more info	PubMed

Process	Evidence Code	Pubs
involved_in flagellated sperm motility	IEA Inferred from Electronic Annotation more info
involved_in in utero embryonic development	IEA Inferred from Electronic Annotation more info
involved_in inositol phosphate metabolic process	TAS Traceable Author Statement more info
involved_in phosphatidylinositol dephosphorylation	IDA Inferred from Direct Assay more info	PubMed
involved_in regulation of protein processing	IEA Inferred from Electronic Annotation more info
involved_in signal transduction	IEA Inferred from Electronic Annotation more info
involved_in spermatogenesis	IEA Inferred from Electronic Annotation more info

Component	Evidence Code	Pubs
located_in Golgi apparatus	IEA Inferred from Electronic Annotation more info
is_active_in cytoplasm	IBA Inferred from Biological aspect of Ancestor more info
is_active_in cytosol	IBA Inferred from Biological aspect of Ancestor more info
located_in cytosol	IDA Inferred from Direct Assay more info	PubMed
located_in early endosome membrane	IEA Inferred from Electronic Annotation more info
located_in endoplasmic reticulum-Golgi intermediate compartment	IEA Inferred from Electronic Annotation more info
is_active_in membrane	IBA Inferred from Biological aspect of Ancestor more info
located_in membrane	IDA Inferred from Direct Assay more info	PubMed
is_active_in neuron projection	IBA Inferred from Biological aspect of Ancestor more info
located_in phagocytic vesicle membrane	IEA Inferred from Electronic Annotation more info
located_in plasma membrane	TAS Traceable Author Statement more info

General protein information

Go to the top of the page Help

Preferred Names: type II inositol 1,4,5-trisphosphate 5-phosphatase

Names: inositol polyphosphate-5-phosphatase, 75kDa; phosphoinositide 5-phosphatase

NP_001284363.1

EC 3.1.3.36

NP_001337156.1

EC 3.1.3.36

NP_001337157.1

EC 3.1.3.36

NP_001352749.1

EC 3.1.3.36

NP_001352750.1

EC 3.1.3.36

NP_001352751.1

EC 3.1.3.36

NP_001352752.1

EC 3.1.3.36

NP_001352753.1

EC 3.1.3.36

NP_001352754.1

EC 3.1.3.36

NP_005531.2

EC 3.1.3.36

XP_011539694.1

EC 3.1.3.36

XP_011539695.1

EC 3.1.3.36

XP_016856695.2

EC 3.1.3.36

XP_054192392.1

EC 3.1.3.36

XP_054192393.1

EC 3.1.3.36

XP_054192394.1

EC 3.1.3.36

NCBI Reference Sequences (RefSeq)

Go to the top of the page Help

NEW Try the new Transcript table

RefSeqs maintained independently of Annotated Genomes

These reference sequences exist independently of genome builds. Explain

These reference sequences are curated independently of the genome annotation cycle, so their versions may not match the RefSeq versions in the current genome build. Identify version mismatches by comparing the version of the RefSeq in this section to the one reported in Genomic regions, transcripts, and products above.

mRNA and Protein(s)

NM_001297434.2 → NP_001284363.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 2 precursor

Status: REVIEWED

Description

Transcript Variant: This variant (2) differs in the 5' UTR, lacks a portion of the 5' coding region, and initiates translation at an alternate start codon, compared to variant 1. The encoded isoform (2) has a distinct N-terminus and is shorter than isoform 1.

Source sequence(s)

AK022846, AL929472, BC042529, BC062317, DC398675

Consensus CDS

CCDS72760.1

UniProtKB/TrEMBL

B3KMW4

Related

ENSP00000362118.1, ENST00000373027.5

Conserved Domains (2) summary

cd09093
Location:101 → 394

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:528 → 748

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...
NM_001350227.2 → NP_001337156.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 3

Status: REVIEWED

Description

Transcript Variant: This variant (3) differs in the 5' UTR, lacks a portion of the 5' coding region, and initiates translation at a downstream in-frame start codon, compared to variant 1. The encoded isoform (3) has a shorter N-terminus than isoform 1. Variants 3 and 4 encode the same protein (isoform 3).

Source sequence(s)

AK022846, AL929472, BC042529, BC062317, DC398675

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (2) summary

cd09093
Location:45 → 338

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:472 → 692

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...
NM_001350228.1 → NP_001337157.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 3

Status: REVIEWED

Description

Transcript Variant: This variant (4) differs in the 5' UTR, lacks a portion of the 5' coding region, and initiates translation at a downstream in-frame start codon, compared to variant 1. The encoded isoform (3) has a shorter N-terminus than isoform 1. Variants 3 and 4 encode the same protein (isoform 3).

Source sequence(s)

AK022846, AL603790, AL929472, BC042529, BC062317, M74161

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (2) summary

cd09093
Location:45 → 338

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:472 → 692

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...
NM_001365820.1 → NP_001352749.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 1 precursor

Status: REVIEWED

Description

Transcript Variant: This variant (5), as well as variant 1, encodes isoform 1.

Source sequence(s)

AL603790, AL929472

Consensus CDS

CCDS41306.1

UniProtKB/Swiss-Prot

C9J6U5, P32019, Q5VSG9, Q5VSH0, Q5VSH1, Q658Q5, Q6P6D4, Q6PD53, Q86YE1

Conserved Domains (3) summary

cd09093
Location:265 → 558

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:692 → 912

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...

pfam16776
Location:6 → 150

INPP5B_PH; Type II inositol 1,4,5-trisphosphate 5-phosphatase PH domain
NM_001365821.1 → NP_001352750.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 4 precursor

Status: REVIEWED

Source sequence(s)

AL603790, AL929472

UniProtKB/Swiss-Prot

C9J6U5, P32019, Q5VSG9, Q5VSH0, Q5VSH1, Q658Q5, Q6P6D4, Q6PD53, Q86YE1

Conserved Domains (3) summary

cd09093
Location:263 → 556

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:690 → 910

RhoGAP_OCRL1; RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate 5-phosphatase domain and ...

pfam16776
Location:6 → 148

INPP5B_PH; Type II inositol 1,4,5-trisphosphate 5-phosphatase PH domain
NM_001365822.1 → NP_001352751.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 5

Status: REVIEWED

Source sequence(s)

AL603790, AL929472

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (3) summary

cd09093
Location:243 → 536

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:670 → 890

RhoGAP_OCRL1; RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate 5-phosphatase domain and ...

cl17171
Location:63 → 128

PH-like; Pleckstrin homology-like domain
NM_001365823.1 → NP_001352752.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 6

Status: REVIEWED

Description

Transcript Variant: This variant (8), as well as variant 9, encodes isoform 6.

Source sequence(s)

AL603790, AL929472

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (3) summary

cd09093
Location:200 → 493

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:627 → 847

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...

cl17171
Location:29 → 85

PH-like; Pleckstrin homology-like domain
NM_001365824.1 → NP_001352753.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 6

Status: REVIEWED

Description

Transcript Variant: This variant (9), as well as variant 8, encodes isoform 6.

Source sequence(s)

AL603790, AL929472

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (3) summary

cd09093
Location:200 → 493

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:627 → 847

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...

cl17171
Location:29 → 85

PH-like; Pleckstrin homology-like domain
NM_001365825.1 → NP_001352754.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 7

Status: REVIEWED

Source sequence(s)

AL603790, AL929472

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (3) summary

cd09093
Location:146 → 439

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:573 → 793

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...

cl17171
Location:1 → 31

PH-like; Pleckstrin homology-like domain
NM_005540.3 → NP_005531.2 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform 1 precursor

Status: REVIEWED

Description

Transcript Variant: This variant (1) encodes the longest isoform (1). Variants 1 and 5 both encode the same isoform (1).

Source sequence(s)

AL603790, AL929472, BC042529, DA125087, M74161

Consensus CDS

CCDS41306.1

UniProtKB/Swiss-Prot

C9J6U5, P32019, Q5VSG9, Q5VSH0, Q5VSH1, Q658Q5, Q6P6D4, Q6PD53, Q86YE1

Related

ENSP00000362115.3, ENST00000373024.8

Conserved Domains (3) summary

cd09093
Location:265 → 558

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:692 → 912

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...

pfam16776
Location:6 → 150

INPP5B_PH; Type II inositol 1,4,5-trisphosphate 5-phosphatase PH domain

RNA

NR_158628.1 RNA Sequence

Status: REVIEWED

Source sequence(s)

AL603790, AL929472
NR_158629.1 RNA Sequence

Status: REVIEWED

Source sequence(s)

AL603790, AL929472
NR_158630.1 RNA Sequence

Status: REVIEWED

Source sequence(s)

AL603790, AL929472
NR_158631.1 RNA Sequence

Status: REVIEWED

Source sequence(s)

AL603790, AL929472

RefSeqs of Annotated Genomes: GCF_000001405.40-RS_2024_08

The following sections contain reference sequences that belong to a specific genome build. Explain

Reference GRCh38.p14 Primary Assembly

Genomic

NC_000001.11 Reference GRCh38.p14 Primary Assembly

Range

37860697..37947057 complement

Download

GenBank, FASTA, Sequence Viewer (Graphics)

mRNA and Protein(s)

XM_011541393.3 → XP_011539695.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform X2

See identical proteins and their annotated locations for XP_011539695.1

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (2) summary

cd09093
Location:72 → 365

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:499 → 719

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...
XM_011541392.3 → XP_011539694.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform X2

See identical proteins and their annotated locations for XP_011539694.1

UniProtKB/TrEMBL

B3KMW4

Conserved Domains (2) summary

cd09093
Location:72 → 365

INPP5c_INPP5B; Catalytic inositol polyphosphate 5-phosphatase (INPP5c) domain of Type II inositol polyphosphate 5-phosphatase I, Oculocerebrorenal syndrome of Lowe 1, and related proteins

cd04380
Location:499 → 719

RhoGAP_OCRL1; RhoGAP_OCRL1: RhoGAP (GTPase-activator protein [GAP] for Rho-like small GTPases) domain present in OCRL1-like proteins. OCRL1 (oculocerebrorenal syndrome of Lowe 1)-like proteins contain two conserved domains: a central inositol polyphosphate ...
XM_017001206.2 → XP_016856695.2 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform X1

RNA

XR_946643.3 RNA Sequence
XR_007059978.1 RNA Sequence
XR_007059977.1 RNA Sequence
XR_946644.4 RNA Sequence

Alternate T2T-CHM13v2.0

Genomic

NC_060925.1 Alternate T2T-CHM13v2.0

Range

37727581..37813950 complement

Download

GenBank, FASTA, Sequence Viewer (Graphics)

mRNA and Protein(s)

XM_054336419.1 → XP_054192394.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform X2
XM_054336418.1 → XP_054192393.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform X2
XM_054336417.1 → XP_054192392.1 type II inositol 1,4,5-trisphosphate 5-phosphatase isoform X1